[llvm] [AMDGPU] Do not count implicit VGPRs in SIInsertWaitcnts (PR #109049)

[Stanislav Mekhanoshin via llvm-commits]

rampitec wrote:

Ideally an operand needs a bit like isArtificial, to distinguish real HW use from the infrastructure dependencies.

https://github.com/llvm/llvm-project/pull/109049