[llvm] [NVPTX] support packed f32 instructions for sm_100+ (PR #126337)

[Nikolay Panchenko via llvm-commits]

npanchen wrote:

> Looks like we need to add the following:
> 
> ```
>   setTruncStoreAction(MVT::v2f32, MVT::v2f16, Expand);
>   setTruncStoreAction(MVT::v2f32, MVT::v2bf16, Expand);
> ```
> 
> Otherwise the fp_round will get folded into the store which we can't handle.

With both https://github.com/llvm/llvm-project/pull/149393 and https://github.com/llvm/llvm-project/pull/149571 my local testing is clean!

https://github.com/llvm/llvm-project/pull/126337