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

[Shilei Tian via cfe-commits]

shiltian 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.

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