[llvm] [OpenMP] Replace most GPU helpers with ones from <gpuintrin.h> (PR #125771)

[Jan Patrick Lehr via llvm-commits]

https://github.com/jplehr requested changes to this pull request.

I saw failures when running this with the `AMDGPUBot.cmake` cache file locally.
Please do not merge.

https://github.com/llvm/llvm-project/pull/125771