[AVX-512] Remove and autoupgrade the masked integer compare intrinsics

Summary:
These intrinsics aren't used by clang and haven't been for a while.

There's some really terrible codegen in the 32-bit target for avx512bw due to i64 not being legal. But as I said these intrinsics aren't used by clang even before this patch so this codegen reflects our clang behavior today.

Reviewers: spatel, RKSimon, zvi, igorb

Reviewed By: RKSimon

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D34389

llvm-svn: 306047