arm64: optimized copy_to_user and copy_from_user assembly code

Using the glibc cortex string work work authored by Linaro as base to
create new copy to/from user kernel routine.

Iperf performance increase:
		-l (size)	1 core result
Optimized 	64B		44-51Mb/s
		1500B		4.9Gb/s
		30000B		16.2Gb/s
Original	64B		34-50.7Mb/s
		1500B		4.7Gb/s
		30000B		14.5Gb/s

Change-Id: I6beac63a65164226f798b043f726fc391ce65e2f
Signed-off-by: Feng Kan <fkan@apm.com>
Patch-mainline: linux-arm-kernel @ 28th April 2015 17:38
Signed-off-by: David Keitel <dkeitel@codeaurora.org>