[NVPTX] Add folding for cvt.rn.bf16x2.f32#116109

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

AlexMaclean:dev/amaclean/upstream-cvt-f16x2AlexMaclean/llvm-project:dev/amaclean/upstream-cvt-f16x2Copy head branch name to clipboard