[X86][llvm-mc] Make the suffix matcher more accurate.

Summary:
Some instruction like VPMULDQ is NOT the variant of VPMULD but a new
one.
So we should make sure the suffix matcher only works for memory variant
that has the same size with the suffix.
Currently we only check for SSE/AVX* instructions, because many legacy
instructions didn't declare the alias instructions of their variants.

Differential Revision: https://reviews.llvm.org/D80608