[llvm] [AMDGPU][MC] Separate VOPC MnemonicAlias from Instruction (PR #89105)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm commented:

Can we just make a PredicateControl'd wrapper for aliases? I believe Mips does that, and I started to make that conversion at some point but never finished 

https://github.com/llvm/llvm-project/pull/89105