[clang] AMDGPU: Rename and add bf16 support for global_load_tr builtins (PR #86202)

[Changpeng Fang via cfe-commits]

changpeng wrote:

I am going to propose to rename intrinsics and remove f16/bf16 versions of builtins/intrinsics

https://github.com/llvm/llvm-project/pull/86202