[AMDGPU] [SIFrameLowering] Use LiveRegUnits instead of LivePhysRegs#65962

prtaneja merged 2 commits intollvm:mainllvm/llvm-project:mainfrom

Pranav-Taneja:SIFrameLoweringLivenessPranav-Taneja/llvm-project:SIFrameLoweringLivenessCopy head branch name to clipboard