[clang] [Clang] Restrict AMDGCN image built-ins (PR #180949)

[Alexey Sachkov via cfe-commits]

AlexeySachkov wrote:

> It won't be pleasant for us or our customers if we have to come back later and expose dmask. I don't see a lot of value to dropping it.

See b3e0d785c856e484f98ec1f0b4bf359347ad4b73, it reverts `dmask` argument removal and instead diagnoses it on all `amdgcn` image intrinsics

https://github.com/llvm/llvm-project/pull/180949