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

[Durgadoss R via llvm-commits]

durga4github wrote:

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

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