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

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> I feel like this is a workaround. Can we not fix the "limitation of the driver" and if there is an issue with HSA overhead, shouldn't we file a ticket?

I don't know for sure, but I'd guess that the limitations seen may be related to the limit of 128 or so doorbells I think we have somewhere. I don't see this as a workaround, it deliberately gets the same information without requiring `/dev/kfd` to be opened. That's unlikely something we'd want to push into HSA.

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