[llvm] [LoongArch] Eliminate the redundant sign extension of division (PR #107971)

[via llvm-commits]

heiher wrote:

The PR created by the cherry-pick bot is always based on the HEAD of the target branch at the time of creation. It seems that backport of PR #107971 needs to be created after the backport PR #107432 is merged. I'm not sure if it's possible to create a combined backport PR for two PRs with dependencies, but if it is, that could also be an option. Thanks for your time and dedication.

https://github.com/llvm/llvm-project/pull/107971