[llvm] [AArch64][TargetParser] move ArchInfo into tablegen [NFC] (PR #92037)

[Alexandros Lamprineas via llvm-commits]

labrinea wrote:

I might be wrong but as far as I understand the TargetParser keeps a list of default extensions per architecture (all the AEK_* entries) trying to model the implied subtarget features we have in tablegen. Since we are now unifying them I don't see the reason to duplicate this information in tablegen itself. We only need to pass the AEK_ equivalent (if it exists) for every implied subtarget feature in the targetparser emitter. I expect that the implied features and the default extensions differ for historical reasons therefore porting them may not be NFC.

https://github.com/llvm/llvm-project/pull/92037