[llvm] [AMDGPU][MC] Improving assembler error message for unsupported instructions (PR #185778)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm commented:

There's generic infrastructure to report the list of required subtarget features, we're just bypassing it. Most of this custom code here should be removable 

https://github.com/llvm/llvm-project/pull/185778