[InstCombine] simplify more code for distributive property; NFCI

Also, fix capitalization to current style. Follow-up to:
rL330096


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@330097 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed