Update the arm64 kernel memcpy/memmove

Bring in the latest Arm Optimized Routines memcpy/memmove into the
arm64 kernel. As these functions have been merged in the current
version remove the now unneeded memmove.S.

Sponsored by: The FreeBSD Foundation

(cherry picked from commit 01e478d9559566e666a7b758ede219ed23d9a833)