[llvm] [AMDGPU] Remove redundant s_cmp_lg_* sX, 0 (PR #162352)

[Jan Patrick Lehr via llvm-commits]

jplehr wrote:

Hi @LU-JOHN, this broke one of our buildbots, and reverting this brings the tests back to working.
Can you look into the breakage? 

You can reproduce the issue (at least on gfx90a) with the following command
```
cd llvm-project
cmake -S llvm -B thebuild -C offload/cmake/caches/AMDGPULibcBot.cmake -GNinja
cd thebuild
ninja
ninja check-libc-amdgcn-amd-amdhsa
```

https://github.com/llvm/llvm-project/pull/162352