[llvm] [NFC][LLVM][PowerPC] Cleanup pass initialization for PowerPC (PR #134422)

[Rahul Joshi via llvm-commits]

jurahul wrote:

Adding @topperc and @s-barannikov as well. This is similar to other changes I made to other backends last week, so hoping one of you can approve.

https://github.com/llvm/llvm-project/pull/134422