[llvm] [AMDGPU] New GFX11+ aliases v_dot4_i32_i8 and v_dot8_i32_i4 (PR #118997)

[Joe Nash via llvm-commits]

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

LGTM. I'm having a hard time even picturing a scenario where having these aliases would confuse someone. Emitting textual assembly on an old target and reassemble it on gfx11? Porting inline asm? 

https://github.com/llvm/llvm-project/pull/118997