[lld] [lld][AArch64] Fix getImplicitAddend in big-endian mode. (PR #107845)

[Peter Smith via llvm-commits]

https://github.com/smithp35 approved this pull request.

LGTM. Apologies for not catching this at the last review. Using readle32 for instructions is what The AArch64ErrataFix uses to disassemble code 

https://github.com/llvm/llvm-project/blob/main/lld/ELF/AArch64ErrataFix.cpp#L413 

https://github.com/llvm/llvm-project/pull/107845