[X86][XOP] Reduce the size of a multiclass by moving more stuff to parameters instead...

[X86][XOP] Reduce the size of a multiclass by moving more stuff to parameters instead of doing 128-bit and 256-bit simultaneously.

This requires some instructions to be renamed to move the Y earlier in the instruction name. The new names are more consistent with other instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295579 91177308-0d34-0410-b5e6-96231b3b80d8