[clang] [llvm] [AMDGPU] Introduce GFX9/10.1/10.3/11 Generic Targets (PR #76955)

[Pierre van Houtryve via cfe-commits]

Pierre-vh wrote:

For the MD changes, it's just to describe the version increment, nothing else. I think describing is important as the V6 diff already updated the amdhsa.version.
If amdhsa.version didn't need to change then i need to fix that first, and then we can remove the V6 MD section

https://github.com/llvm/llvm-project/pull/76955