[X86] Add '.s' aliases to the assembler for the various redundant move...

[X86] Add '.s' aliases to the assembler for the various redundant move encodings to match gas and our EVEX instructions.

We already have these aliases for EVEX enocded instructions, but not for the GPR, MMX, SSE, and VEX versions.

Also remove the vpextrw.s EVEX alias. That's not something gas implements.

llvm-svn: 334922