[InstCombine] remove icmp shr folds that are already handled by InstSimplify

AFAICT, these already worked in all cases for scalar types, and I enhanced
the code to work for vector types in:
https://reviews.llvm.org/rL279543


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279568 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed