[llvm] [AArch64AsmParser] Allow branch target symbol to have a shift/extend modifier name (PR #80571)

[David Green via llvm-commits]

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

I'm not really an assembler expert, but this looks sensible from what I can see. LGTM

https://github.com/llvm/llvm-project/pull/80571