x86: re-arrange enumerator and table entry order

Some of the enumerators have ended up misplaced under the general
current ordering scheme. Move them (and their table entries) around
accordingly. Add a couple of blank lines as separators when close to
code being touched anyway. Also drop the odd 0F from 0FXOP (there's no
"0f" involved there anywhere) infixes where the respective enum gets
played with anyway.