[llvm] [PowerPC] Conversions of f128 and f16 should use _kf_ instead of _tf_ (PR #99855)

[Trevor Gross via llvm-commits]

tgross35 wrote:

https://github.com/llvm/llvm-project/pull/130158 landed in place of #97677, I think this should be ready with a rebase

https://github.com/llvm/llvm-project/pull/99855