[llvm] [AMDGPU][wmma] - Add tied wmma intrinsic (PR #69903)

[Piotr Sobczak via llvm-commits]

piotrAMD wrote:

Would "preserve" be a better suffix, as in "preserve the other half"?

Need to add clang builtins too, similarly to [D128952](https://reviews.llvm.org/D128952) (can be a separate patch).

https://github.com/llvm/llvm-project/pull/69903