Replace memcpy with the cortex-strings implementation

Benchmarks on a Nexus 10 have shown this implementation to be
up to 12% faster.

Change-Id: Ida882cc6a583dfd00c3659b022c26070665824af
Signed-off-by: Bernhard Rosenkränzer <Bernhard.Rosenkranzer@linaro.org>
krait: use A15 memchr

Change-Id: I6d9c773612db02706d5a36252eb7d4458d9b6e1b