[clang] [llvm] [AMDGPU] Builtins and intrinsics for v_cvt_scalef32_pk32_(fp|bf)6_f32 (PR #210713)

[Shilei Tian via cfe-commits]

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

LGTM modulo @arsenm's comment about target triple.

https://github.com/llvm/llvm-project/pull/210713