[llvm] AArch64: Clean up relocation error messages. (PR #138625)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> Also, remove "LP64 eqv:" annotations because they create a maintenance burden and are unlikely to be helpful.

Agreed. The issue will likely be self-inflicted and it's not too difficult to grep the message within the llvm-project source.

https://github.com/llvm/llvm-project/pull/138625