RISC-V: Print XTheadMemPair literal as "immediate"

The operand type "Xl(...)" denotes that (...) is a literal.  Specifically,
they are intended to be a constant immediate value.

This commit prints "Xl(...)" operand with dis_style_immediate style,
not dis_style_text.

opcodes/ChangeLog:

	* riscv-dis.c (print_insn_args): Use dis_style_immediate on
	the constant literal of the "Xl..." operand.
diff --git a/opcodes/riscv-dis.c b/opcodes/riscv-dis.c
index 9d73356..27a6bfe 100644
--- a/opcodes/riscv-dis.c
+++ b/opcodes/riscv-dis.c
@@ -578,7 +578,7 @@
 		  oparg++;
 		  while (*oparg && *oparg != ',')
 		    {
-		      print (info->stream, dis_style_text, "%c", *oparg);
+		      print (info->stream, dis_style_immediate, "%c", *oparg);
 		      oparg++;
 		    }
 		  oparg--;