[llvm] Revert "[AArch64] Define high bits of FPR and GPR registers (take 2) (#114827)" (PR #117307)

[Sander de Smalen via llvm-commits]

https://github.com/sdesmalen-arm approved this pull request.

Strictly speaking not all patches need reverting (like the changes to InitUndef or RegisterCoalescer), although without the AArch64 changes that would mean those changes would no longer have any tests. I'll reland all these after I've investigated the issue caused by this patch.

Thanks for creating the revert.

https://github.com/llvm/llvm-project/pull/117307