[llvm] [AMDGPU] Refactor GFX11 VALU Mask Hazard Waitcnt Merging (PR #169213)

[Carl Ritson via llvm-commits]

perlfu wrote:

> LGTM overall though I don't claim to understand all the details

Thanks, I appreciate your feedback.
Unfortunately I might be the only person who understands these hazards -- or at least their mitigation structure.

https://github.com/llvm/llvm-project/pull/169213