[Driver] Reject -march= for ppc

Clang -march= for ppc triples currently leads to an
-Wunused-command-line-argument warning but GCC rejects -march=.

    error: unrecognized command-line option ‘-march=xxx’

Let's reject -march= as well similar to the Sparc change D130273.

Close https://github.com/llvm/llvm-project/issues/57587

Reviewed By: #powerpc, nemanjai

Differential Revision: https://reviews.llvm.org/D145141