[llvm] [AMDGPU] Use the SchedModel available in SIInstrInfo (PR #110859)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm approved this pull request.

LGTM. I don't think we should have this copy in TargetInstrInfo, it's already present in the MCSubtargetInfo 

https://github.com/llvm/llvm-project/pull/110859