[llvm] [AMDGPU] Change the immediate operand of s_waitcnt_depctr / s_wait_alu (PR #169378)

[Carl Ritson via llvm-commits]

perlfu wrote:

> I have run Vulkan CTS testing on Navi31 + Navi33 + Navi48 with no failures. Is that good enough?

Thanks, that's reassuring.
I'm not really expecting any smoke to come out.
However, I wonder if we couldn't just create a representation of the unused bits that work the same as real counters, e.g. depctr_unused.
Then they would default to 1 (for GFX10.3 onward)?
But maybe I misunderstood the `DepCtrInfo` table code.

https://github.com/llvm/llvm-project/pull/169378