x86: adjust register names printed for MONITOR/MWAIT

x86: adjust register names printed for MONITOR/MWAIT

As the comments (here: almost, in the opcode table: fully) correctly
state - all register operands except MONITOR's address one are fixed
at 32 bit size. Don't print 64-bit registers there.

Also adjust x86-64-suffix.d's name such that it wouldn't be identical to
x86-64-rep-suffix.d's, but instead resemble that of its sibling
x86-64-suffix-intel.d.