[llvm] [NVPTX] Add some more immediate instruction variants (PR #122746)

[Alex MacLean via llvm-commits]

AlexMaclean wrote:

> Can we get some tests for the other new cases as well? And it would be nice to have a case showing the folding of the iii type too if we don't already have one somewhere.

Sounds good, I've added tests for both these requests.

https://github.com/llvm/llvm-project/pull/122746