[CVP] processCallSite returns wrong status

Recently processMinMaxIntrinsic has been added and we started to observe a number of analysis get invalidated after CVP. The problem is CVP conservatively returns 'true'  even if there were no modifications to IR. I found one more place besides processMinMaxIntrinsic  which has the same problem. I think processMinMaxIntrinsic and similar should better have boolean return status to prevent similar issue reappear in future.

Reviewed By: lebedev.ri

Differential Revision: https://reviews.llvm.org/D100538