[llvm] [AMDGPU] Lower `llvm.amdgcn.queue.ptr` instrinsic to using implicit kernel argument if feasible (PR #103490)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> But the thing is, the two SGPRs are never set in COV5. If you still want to use them, you basically have to revert those patches that @changpeng has done to disable allocation of the two SGPRs completely in COV5.

Yes. It is still possible to use the queue pointer. You could still want to use the queue pointer as a preloaded argument. 

https://github.com/llvm/llvm-project/pull/103490