[llvm] [NVPTX] Fix NaN + overflow semantics of f2ll/d2i (PR #159530)

[Lewis Crawford via llvm-commits]

LewisCrawford wrote:

> Does the behaviour _changed_ in PTX9.0, or did the instructions already behave that way and only got documented in PTX9.0?

The documentation was updated to match the behaviour that was always actually happening in practice. So there should be no need to check the PTX-version here.

https://github.com/llvm/llvm-project/pull/159530