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

[Qiu Chaofan via llvm-commits]

ecnelises wrote:

Seems this is not rebased upon #97677? After #97677 lands, this will only have https://github.com/llvm/llvm-project/commit/40b97f3d5a5cfda323b84ffe89b42fe2ebd410c3. That commit looks good to me.

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