[llvm] [LoongArch] Simplily fix extractelement on LA32 (PR #159564)

[via llvm-commits]

https://github.com/heiher commented:

Thanks for fixing LA32. There’s an ongoing branch working on fixing the LA32 vector. Since the work isn’t complete yet, no PR has been opened. In the meantime, feel free to submit separate PRs for individual test issues that are blocking progress.

https://github.com/heiher/llvm-project/commits/la32-vec

https://github.com/llvm/llvm-project/pull/159564