[llvm] [AVR] Fix SETUGT during 128b -> 64b lowering (PR #182690)

[Patryk Wychowaniec via llvm-commits]

Patryk27 wrote:

> It would be better to make the commit message more brief. 

Actually, the commit message itself is empty (except for the commit title itself) - the description above I've filled out only on GitHub to make the review easier, I think it won't be visible after the merge 👀 

https://github.com/llvm/llvm-project/pull/182690