Add optimized version of memcmp for Cortex A9

Adds new code to function memcmp, optimized for Cortex A9.

Copyright (C) ST-Ericsson SA 2010

Added neon optimization

Change-Id: I8864d277042db40778b33232feddd90a02a27fb0
Author: Henrik Smiding henrik.smiding@stericsson.com for ST-Ericsson.
Signed-off-by: Christian Bejram <christian.bejram@stericsson.com>