[llvm] [NVPTX] Further refactor intrinsic definitions to remove redundancy (NFC) (PR #139924)

[Artem Belevich via llvm-commits]

Artem-B wrote:

I agree, only conversion intrinsics are affected, no need to special case them. Everything else looks fine when we look at the file with the change applied..

> the only place I see where there seems like a problem is the type-conversion intrinsics. 

That's what prompted my comment. Looking at it as a diff also made things look worse, as the new changes were spread around by removed chunks on the left side of the diff. E.g. fma: 
![image](https://github.com/user-attachments/assets/491de425-35c0-4ccd-9130-5ab2b4bdb574)



https://github.com/llvm/llvm-project/pull/139924