[llvm] [PowerPC] Utilize getReservedRegs to find asm clobberable registers. (PR #107863)

[Lei Huang via llvm-commits]

https://github.com/lei137 approved this pull request.

In general this looks LGTM.  Just one more nit.
Maybe give it a few days to see if anyone else have additional comments before committing.

Thx

https://github.com/llvm/llvm-project/pull/107863