[PowerPC] Allow llvm.ppc.cfence to accept pointer types

In the context of atomic load, integer, pointer and float point types are allowed, thus we should allow llvm.ppc.cfence to accept any type mentioned.

Fixes https://github.com/llvm/llvm-project/issues/55983.

Reviewed By: shchenz, vchuravy

Differential Revision: https://reviews.llvm.org/D127554