[llvm] [mlir] [MLIR][NVVM][NVPTX] Support intrinsics about stmatrix (PR #148377)

[Mario Lezcano Casado via llvm-commits]

lezcano wrote:

There are equivalent instrucctions for `ldmatrix`, will these go in a different PR?
At any rate, thank you for this contribution!

https://github.com/llvm/llvm-project/pull/148377