[llvm] Reland "[NVPTX] Legalize aext-load to zext-load to expose more DAG combines" (PR #155063)

[Alex MacLean via llvm-commits]

AlexMaclean wrote:

> Seems fine, were you able to test the libc stuff locally?

Yep! I was able to reproduce the regression and confirm that there are no errors with this version of the change.

https://github.com/llvm/llvm-project/pull/155063