[X86][AVX512] Updated shuffle comments instruction macros to split writemask instructions. NFC

This will make it easier to support the different writemask cases in shuffle comments

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269174 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed