Revert "[AArch64] Async unwind - Adjust unwind info in AArch64LoadStoreOptimizer"

This reverts commit ecbf32dd.

It's possible this patch is the reason for an asertion failure
`!NodePtr->isKnownSentinel()` in `AArch64LoadStoreOpt::mergeUpdateInsn`
(https://lab.llvm.org/buildbot/#/builders/185/builds/1555) reverting while I
investigate.