[llvm] [AArch64][ISel] Add support for v8.4a RCpc `ldapur`/`stlur` (PR #67879)

[Florian Hahn via llvm-commits]

fhahn wrote:

Thanks for the fix, I looks like this still needs a test case (also left a comment a the commit)

https://github.com/llvm/llvm-project/pull/67879