[clang] [llvm] [AMDGPU] Add support for `v_cos_bf16_e64` on gfx1250 (PR #149355)

[Changpeng Fang via cfe-commits]

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

LGTM. Changed subject to "v_cos_bf16_e64" based on the contents.

https://github.com/llvm/llvm-project/pull/149355