[mlir][LLVM] erase call mappings in forgetMapping() (#84955)

It looks like the mappings for call instructions were forgotten here.
This fixes a bug in OpenMP when in-lining a region containing call
operations multiple times.

OpenMP array reductions 4/6
Previous PR: https://github.com/llvm/llvm-project/pull/84954
Next PR: https://github.com/llvm/llvm-project/pull/84957