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: I1c1ec6403e7e5c040c1528511578888cb1e77379
Signed-off-by: Feng Kan <fkan@apm.com>
Patch-mainline: linux-arm-kernel @ 8 Aug 2014 16:02
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>