[NVPTX] Consolidate and cleanup various NVPTXISD nodes (NFC)#145581

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

AlexMaclean:dev/amaclean/upstream/cleanup-dead-nodesAlexMaclean/llvm-project:dev/amaclean/upstream/cleanup-dead-nodesCopy head branch name to clipboard