[InstCombine] change param type from Instruction to BinaryOperator for icmp helpers; NFCI

This saves some casting in the helper functions and eases some further refactoring.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279478 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed