MIPS/opcodes: Output thread context registers numerically with MFTR/MTTR

We print MFTR and MTTR instructions' thread context register operand in
disassembly using the ABI name the register number would correspond to
should the targeted register be a general-purpose register.

However in most cases it is wrong, because general-purpose registers are
only referred when the 'u' and 'sel' operands are 1 and 0 respectively.
And even in these cases the MFGPR and MTGPR aliases take precedence over
the corresponding generic instruction encodings, so you won't see the
valid case to normally trigger.

Conversely decoding the thread context register operand numerically is
always valid, so switch to using it.  Adjust test coverage accordingly.
diff --git a/gas/testsuite/gas/mips/mips32-mt.d b/gas/testsuite/gas/mips/mips32-mt.d
index b514021..80e11f1 100644
--- a/gas/testsuite/gas/mips/mips32-mt.d
+++ b/gas/testsuite/gas/mips/mips32-mt.d
@@ -574,30 +574,30 @@
 0+08d0 <[^>]*> 410e6805 	mftc0	t5,\$14,5
 0+08d4 <[^>]*> 410e6806 	mftc0	t5,\$14,6
 0+08d8 <[^>]*> 410e6807 	mftc0	t5,\$14,7
-0+08dc <[^>]*> 410e6810 	mftr	t5,t6,0,0,1
-0+08e0 <[^>]*> 410e6811 	mftr	t5,t6,0,1,1
-0+08e4 <[^>]*> 410e6812 	mftr	t5,t6,0,2,1
-0+08e8 <[^>]*> 410e6813 	mftr	t5,t6,0,3,1
-0+08ec <[^>]*> 410e6814 	mftr	t5,t6,0,4,1
-0+08f0 <[^>]*> 410e6815 	mftr	t5,t6,0,5,1
-0+08f4 <[^>]*> 410e6816 	mftr	t5,t6,0,6,1
-0+08f8 <[^>]*> 410e6817 	mftr	t5,t6,0,7,1
+0+08dc <[^>]*> 410e6810 	mftr	t5,\$14,0,0,1
+0+08e0 <[^>]*> 410e6811 	mftr	t5,\$14,0,1,1
+0+08e4 <[^>]*> 410e6812 	mftr	t5,\$14,0,2,1
+0+08e8 <[^>]*> 410e6813 	mftr	t5,\$14,0,3,1
+0+08ec <[^>]*> 410e6814 	mftr	t5,\$14,0,4,1
+0+08f0 <[^>]*> 410e6815 	mftr	t5,\$14,0,5,1
+0+08f4 <[^>]*> 410e6816 	mftr	t5,\$14,0,6,1
+0+08f8 <[^>]*> 410e6817 	mftr	t5,\$14,0,7,1
 0+08fc <[^>]*> 410e6820 	mftgpr	t5,t6
 0+0900 <[^>]*> 410e6821 	mftacx	t5,\$ac3
 0+0904 <[^>]*> 410e6822 	mftc1	t5,\$f14
 0+0908 <[^>]*> 410e6823 	cftc1	t5,\$14
 0+090c <[^>]*> 410e6824 	mftc2	t5,\$14
 0+0910 <[^>]*> 410e6825 	cftc2	t5,\$14
-0+0914 <[^>]*> 410e6826 	mftr	t5,t6,1,6,0
-0+0918 <[^>]*> 410e6827 	mftr	t5,t6,1,7,0
-0+091c <[^>]*> 410e6830 	mftr	t5,t6,1,0,1
-0+0920 <[^>]*> 410e6831 	mftr	t5,t6,1,1,1
+0+0914 <[^>]*> 410e6826 	mftr	t5,\$14,1,6,0
+0+0918 <[^>]*> 410e6827 	mftr	t5,\$14,1,7,0
+0+091c <[^>]*> 410e6830 	mftr	t5,\$14,1,0,1
+0+0920 <[^>]*> 410e6831 	mftr	t5,\$14,1,1,1
 0+0924 <[^>]*> 410e6832 	mfthc1	t5,\$f14
-0+0928 <[^>]*> 410e6833 	mftr	t5,t6,1,3,1
+0+0928 <[^>]*> 410e6833 	mftr	t5,\$14,1,3,1
 0+092c <[^>]*> 410e6834 	mfthc2	t5,\$14
-0+0930 <[^>]*> 410e6835 	mftr	t5,t6,1,5,1
-0+0934 <[^>]*> 410e6836 	mftr	t5,t6,1,6,1
-0+0938 <[^>]*> 410e6837 	mftr	t5,t6,1,7,1
+0+0930 <[^>]*> 410e6835 	mftr	t5,\$14,1,5,1
+0+0934 <[^>]*> 410e6836 	mftr	t5,\$14,1,6,1
+0+0938 <[^>]*> 410e6837 	mftr	t5,\$14,1,7,1
 0+093c <[^>]*> 418d7000 	mttc0	t5,c0_epc
 0+0940 <[^>]*> 418d7001 	mttc0	t5,\$14,1
 0+0944 <[^>]*> 418d7002 	mttc0	t5,\$14,2
@@ -606,29 +606,29 @@
 0+0950 <[^>]*> 418d7005 	mttc0	t5,\$14,5
 0+0954 <[^>]*> 418d7006 	mttc0	t5,\$14,6
 0+0958 <[^>]*> 418d7007 	mttc0	t5,\$14,7
-0+095c <[^>]*> 418d7010 	mttr	t5,t6,0,0,1
-0+0960 <[^>]*> 418d7011 	mttr	t5,t6,0,1,1
-0+0964 <[^>]*> 418d7012 	mttr	t5,t6,0,2,1
-0+0968 <[^>]*> 418d7013 	mttr	t5,t6,0,3,1
-0+096c <[^>]*> 418d7014 	mttr	t5,t6,0,4,1
-0+0970 <[^>]*> 418d7015 	mttr	t5,t6,0,5,1
-0+0974 <[^>]*> 418d7016 	mttr	t5,t6,0,6,1
-0+0978 <[^>]*> 418d7017 	mttr	t5,t6,0,7,1
+0+095c <[^>]*> 418d7010 	mttr	t5,\$14,0,0,1
+0+0960 <[^>]*> 418d7011 	mttr	t5,\$14,0,1,1
+0+0964 <[^>]*> 418d7012 	mttr	t5,\$14,0,2,1
+0+0968 <[^>]*> 418d7013 	mttr	t5,\$14,0,3,1
+0+096c <[^>]*> 418d7014 	mttr	t5,\$14,0,4,1
+0+0970 <[^>]*> 418d7015 	mttr	t5,\$14,0,5,1
+0+0974 <[^>]*> 418d7016 	mttr	t5,\$14,0,6,1
+0+0978 <[^>]*> 418d7017 	mttr	t5,\$14,0,7,1
 0+097c <[^>]*> 418d7020 	mttgpr	t5,t6
 0+0980 <[^>]*> 418d7021 	mttacx	t5,\$ac3
 0+0984 <[^>]*> 418d7022 	mttc1	t5,\$f14
 0+0988 <[^>]*> 418d7023 	cttc1	t5,\$14
 0+098c <[^>]*> 418d7024 	mttc2	t5,\$14
 0+0990 <[^>]*> 418d7025 	cttc2	t5,\$14
-0+0994 <[^>]*> 418d7026 	mttr	t5,t6,1,6,0
-0+0998 <[^>]*> 418d7027 	mttr	t5,t6,1,7,0
-0+099c <[^>]*> 418d7030 	mttr	t5,t6,1,0,1
-0+09a0 <[^>]*> 418d7031 	mttr	t5,t6,1,1,1
+0+0994 <[^>]*> 418d7026 	mttr	t5,\$14,1,6,0
+0+0998 <[^>]*> 418d7027 	mttr	t5,\$14,1,7,0
+0+099c <[^>]*> 418d7030 	mttr	t5,\$14,1,0,1
+0+09a0 <[^>]*> 418d7031 	mttr	t5,\$14,1,1,1
 0+09a4 <[^>]*> 418d7032 	mtthc1	t5,\$f14
-0+09a8 <[^>]*> 418d7033 	mttr	t5,t6,1,3,1
+0+09a8 <[^>]*> 418d7033 	mttr	t5,\$14,1,3,1
 0+09ac <[^>]*> 418d7034 	mtthc2	t5,\$14
-0+09b0 <[^>]*> 418d7035 	mttr	t5,t6,1,5,1
-0+09b4 <[^>]*> 418d7036 	mttr	t5,t6,1,6,1
-0+09b8 <[^>]*> 418d7037 	mttr	t5,t6,1,7,1
+0+09b0 <[^>]*> 418d7035 	mttr	t5,\$14,1,5,1
+0+09b4 <[^>]*> 418d7036 	mttr	t5,\$14,1,6,1
+0+09b8 <[^>]*> 418d7037 	mttr	t5,\$14,1,7,1
 0+09bc <[^>]*> 00000140 	pause
 	\.\.\.
diff --git a/opcodes/mips-opc.c b/opcodes/mips-opc.c
index 2ee2983..6389301 100644
--- a/opcodes/mips-opc.c
+++ b/opcodes/mips-opc.c
@@ -1420,7 +1420,7 @@
 {"mfthi",		"d,*",		0x41010021, 0xfff307ff, WR_1|RD_a|TRAP,		0,		0,		MT32,	0 },
 {"mftlo",		"d",		0x41000021, 0xffff07ff, WR_1|RD_a|TRAP,		0,		0,		MT32,	0 },
 {"mftlo",		"d,*",		0x41000021, 0xfff307ff, WR_1|RD_a|TRAP,		0,		0,		MT32,	0 },
-{"mftr",		"d,t,!,H,$",	0x41000000, 0xffe007c8, WR_1|TRAP,		0,		0,		MT32,	0 },
+{"mftr",		"d,E,!,H,$",	0x41000000, 0xffe007c8, WR_1|TRAP,		0,		0,		MT32,	0 },
 {"mfc0",		"t,G",		0x40000000, 0xffe007ff,	WR_1|RD_C0|LC,		0,		I1,		0,	0 },
 {"mfc0",		"t,G,H",	0x40000000, 0xffe007f8,	WR_1|RD_C0|LC,		0,		I32,		0,	0 },
 {"mfgc0",		"t,G",		0x40600000, 0xffe007ff,	WR_1|RD_C0|LC,		0,		0,		IVIRT,	0 },
@@ -1577,7 +1577,7 @@
 {"mtthi",		"t,&",		0x41800821, 0xffe09fff, RD_1|WR_a|TRAP,		0,		0,		MT32,	0 },
 {"mttlo",		"t",		0x41800021, 0xffe0ffff, RD_1|WR_a|TRAP,		0,		0,		MT32,	0 },
 {"mttlo",		"t,&",		0x41800021, 0xffe09fff, RD_1|WR_a|TRAP,		0,		0,		MT32,	0 },
-{"mttr",		"t,d,!,H,$",	0x41800000, 0xffe007c8, RD_1|TRAP,		0,		0,		MT32,	0 },
+{"mttr",		"t,G,!,H,$",	0x41800000, 0xffe007c8, RD_1|TRAP,		0,		0,		MT32,	0 },
 {"mul.d",		"D,V,T",	0x46200002, 0xffe0003f,	WR_1|RD_2|RD_3|FP_D,	0,		I1,		0,	SF },
 {"mul.s",		"D,V,T",	0x46000002, 0xffe0003f,	WR_1|RD_2|RD_3|FP_S,	0,		I1,		0,	0 },
 {"mul.ob",		"X,Y,Q",	0x78000030, 0xfc20003f,	WR_1|RD_2|RD_3|FP_D,	0,		SB1,		MX,	0 },