Revert r329956, "AArch64: Introduce a DAG combine for folding offsets into addresses."

Caused a hang and eventually an assertion failure in LTO builds
of 7zip-benchmark on aarch64 iOS targets.
http://green.lab.llvm.org/green/job/lnt-ctmark-aarch64-O3-flto/2024/

llvm-svn: 330063