arm64: lib: Implement optimized memmove routine

This patch, based on Linaro's Cortex Strings library, improves
the performance of the assembly optimized memmove() function.

Signed-off-by: Zhichang Yuan <zhichang.yuan@linaro.org>
Signed-off-by: Deepak Saxena <dsaxena@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Git-commit: 280adc1951c0c9fc8f2d85571ff563a1c412b1cd
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>