[llvm] [NVPTX] Add intrinsics for wgmma.fence PTX instructions (PR #120523)

[Srinivasa R via llvm-commits]

Wolfram70 wrote:

> @Wolfram70 , Can you confirm the generated ptx compiles smoothly with 12.0 ptxas ? (using the LLVM_PTXAS_EXECUTABLE option)

Yes, I have verified that it passes through ptxas without issues.

https://github.com/llvm/llvm-project/pull/120523