arm64: lib: memory utilities optimization

Optimize memcpy and memmove, to prefetch several cache lines.
We can achieve 15% memcpy speed improvement with the preload method.

Change-Id: I2259b98a33eba0b7466920b3f270f953e609cf13
Signed-off-by: Hong-Mei Li <a21834@motorola.com>
Reviewed-on: http://gerrit.mot.com/740766


SLTApproved: Slta Waiver <sltawvr@motorola.com>
SME-Granted: SME Approvals Granted
Tested-by: Jira Key <jirakey@motorola.com>
Reviewed-by: Zhi-Ming Yuan <a14194@motorola.com>
Submit-Approved: Jira Key <jirakey@motorola.com>