[llvm] [NVPTX] Add truncate and zero-extend free type conversions (PR #125580)

[Justin Fargnoli via llvm-commits]

================
@@ -150,6 +150,28 @@ class NVPTXTargetLowering : public TargetLowering {
            DstTy->getPrimitiveSizeInBits() == 32;
----------------
justinfargnoli wrote:

```suggestion
    if (SrcTy->getPrimitiveSizeInBits() <= DstTy->getPrimitiveSizeInBits())
      return false;
    return ToVT.getSizeInBits() % 32 == 0;
```

https://github.com/llvm/llvm-project/pull/125580