[llvm] [X86] Lower mathlib call ldexp into scalef when avx512 is enabled (PR #69710)

[via llvm-commits]

huhu233 wrote:

* Rebase the branch
* Use `X86ISD::SCALEFS` instead of specific intrinsics
* Transfrom the function into static version
* update the test file 

https://github.com/llvm/llvm-project/pull/69710