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

[Artem Belevich via llvm-commits]

https://github.com/Artem-B approved this pull request.

Nice to see those tex/surf intrinsics combined into something less verbose.
Setting intrinsic attributes via encompassing `let` is a mixed blessing.
It's fine for smaller blocks, where one can see them.

They are a bit of a regression in terms of readability for larger blocks, as it makes it too easy to look at an intrinsic, and completely miss the attributes that are set somewhere else, out of view. Considering that those properties are critical for the intrinsics, it's not ideal.

Not sure whether it's something we need to fix -- large-block `let` already exist in other places, so we can certainly live with it, but it would be nice if we could keep relevant info easily visible where it matters. Perhaps we could apply `let` over parts of particularly large blocks. It will be redundant, but may work well enough for keeping things readable. WDYT?

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