[AVX512] Refactoring of avx512_binop_rm multiclass through AVX512_masking.
Added new argrument for AVX512_masking: InstrItinClass and bit isCommutable.
No functional change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219310 91177308-0d34-0410-b5e6-96231b3b80d8