[AVX-512] Remove explicit KMOVWrk/KMOVWKr instructions from patterns where we can...

[AVX-512] Remove explicit KMOVWrk/KMOVWKr instructions from patterns where we can just use COPY_TO_REGCLASS instead.

This will result in a KMOVW or KMOVD being emitted during register allocation. And in at least some cases this might allow the register coalescer to remove the copy all together.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@298984 91177308-0d34-0410-b5e6-96231b3b80d8