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

[Matt Arsenault via cfe-commits]

arsenm wrote:

> > Here's a question, should it respect `ROCR_VISIBLE_DEVICES`?

No. That is a transient runtime debug flag. This is not executing code on the device 

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