x86: misc further memory-only insns don't need to go through mod_table[]

Several already use OP_M(), which rejects the register forms of insns,
and a few others can easily be converted to do so as well. (Note that
FXSAVE_Fixup() wires through to OP_M(). Note further that OP_IndirE(),
which wasn't placed very well anyway, is moved down to avoid the need to
forward-declare BadOp().)

Also adjust formatting of and drop PREFIX_OPCODE from a few adjacent
entries.