arm: lib: Fix makefile issue
Fix the typo introduced by commit fb7051a.

Change-Id: Ia23c80f903ed431e60e4ba17c9c6d527e6febd87
Signed-off-by: Hong-Mei Li <a21834@motorola.com>
Reviewed-on: http://gerrit.pcs.mot.com/527915
SLT-Approved: Gerrit Code Review <gerrit-blurdev@motorola.com>
Tested-by: Jira Key <jirakey@motorola.com>
Reviewed-by: Christopher Fries <qcf001@motorola.com>
Submit-Approved: Jira Key <jirakey@motorola.com>
Revert "revert "arch: arm: lib: optimize memcpy for cortex-A15""

This reverts commit 0d4005ec6ff2cd9c892accdcb700c022f857def7.