[NVPTX] Cleanup various vestigial elements and fold together more table-gen (NFC)#151447

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

AlexMaclean:dev/amaclean/nfc-cleanup-730AlexMaclean/llvm-project:dev/amaclean/nfc-cleanup-730Copy head branch name to clipboard