[llvm] AMDGPU: Make bf16/v2bf16 legal types (PR #76215)

[Stanislav Mekhanoshin via llvm-commits]

https://github.com/rampitec approved this pull request.

LGTM, although I do not believe we can finally make bfloat16 legal in an FE now, we will still have a lot of emulation for many operations. I.e. if the final plan is to switch from i16 to bf16 in intrinsics and builtins, that is hardly possible. At best we will need to start with overloaded interfaces supporting both.

https://github.com/llvm/llvm-project/pull/76215