[X86] Correct 256 vpmovzx/vpmovsx isel patterns to check HasAVX2 instead of HasAVX to prevent fast-isel from using them incorrectly.

These are AVX2 instructions, but have been incorrectly marked in tablegen for a while. This wasn't a problem until r346784 switched the patterns to use target independent ISD opcodes. This made the patterns visible to fast isel.

Fixes PR39733

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@347375 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed