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

[Chen Zheng via llvm-commits]

chenzheng1030 wrote:

> @chenzheng1030 would you be able to take a look at the second commit ([40b97f3](https://github.com/llvm/llvm-project/commit/40b97f3d5a5cfda323b84ffe89b42fe2ebd410c3)) here, for merge after #97677?

I am waiting for the first patch being merged and the second one being rebased.

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