[X86] Replace usages of X86Subtarget::hasFp256 with hasAVX. Remove hasFP256.

Almost none of these usages were FP specific. And we had no clear guideliness on when to use hasAVX vs hasFP256.

I might also remove hasInt256 too since its an alias for hasAVX2.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@326682 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed