[clang] [amdgpu-arch] Replace use of HSA with reading sysfs directly (PR #116651)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> > Here's a question, should it respect `ROCR_VISIBLE_DEVICES`?
> 
> I think it depends on whether you consider this as a ROCm toolchain. If not, I'd prefer not to be bound to any ROCm related stuff.

Agreed, maybe in the fork but makes sense to leave community LLVM alone.

https://github.com/llvm/llvm-project/pull/116651