[clang] [AMDGPU] Check wavefrontsize for GFX11 WMMA builtins (PR #79980)

[Jay Foad via cfe-commits]

jayfoad wrote:

> Do you think it makes sense to add two gfx11 tests where _w32 variant is now rejected with w64, and _w64 variant rejected with w32?

Maybe, but i didn't have the energy to add yet more tests.

> Maybe what is being printed in *-gfx10-err.cl test is enough, though.

Right, that was my thinking.

https://github.com/llvm/llvm-project/pull/79980