[AMDGPU] Use correct SlotIndex to calculate live-out register set.#161720

vpykhtin merged 3 commits intollvm:mainllvm/llvm-project:mainfrom

vpykhtin:fix_liveouts_add_getMBBLastIdxvpykhtin/llvm-project:fix_liveouts_add_getMBBLastIdxCopy head branch name to clipboard