Revert "Add optimized AArch64 versions of bcopy and wmemmove based on memmove"

This reverts commit 8167dd7c.

For some reason I thought the bcopy change was bzero. The bcopy code doesn't pass our tests, so reverting until I can figure out what's wrong.

Change-Id: Id89fe959ea5105cd58dff6bba8d91a30cc4bcb07