[llvm] Revert "[AMDGPU] MCExpr-ify MC layer kernel descriptor" (PR #86151)

[Janek van Oirschot via llvm-commits]

JanekvO wrote:

> If you have a fix ready thats fine too. Just FYI, you generally don't need to create a PR for a revert, you can just do it.
> 
> LGTM.

Ah, apologies. Will do so next time; didn't know that the github web-interface revert would trigger a PR the same way as any other change would.

Thanks

https://github.com/llvm/llvm-project/pull/86151