[llvm] [NVPTX] Add patterns for fma.relu.{f16|bf16} (PR #114977)

[Justin Fargnoli via llvm-commits]

https://github.com/justinfargnoli approved this pull request.

Overall, LGTM! 

Please wait for @AlexMaclean's review though as he's more familiar with `NVPTXInstrInfo.td` than I am. 

https://github.com/llvm/llvm-project/pull/114977