[clang] [NFC][PowerPC][clang] Update clang/test/Driver/aix-default-target-triple.c for AIX specific targets (PR #147584)

[Hubert Tong via cfe-commits]

https://github.com/hubert-reinterpretcast approved this pull request.

LGTM with suggested changes.

https://github.com/llvm/llvm-project/pull/147584