[TargetLowering] isVectorClearMaskLegal - use ArrayRef<int> instead of const SmallVectorImpl<int>&

This is more generic and matches isShuffleMaskLegal.

Differential Revision: https://reviews.llvm.org/D48591

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@335605 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed