create 'memcpy' and 'memset' functions for SPM and core. Apply them in SPM and core.
https://review.trustedfirmware.org/#/c/trusted-firmware-m/+/2116/ https://review.trustedfirmware.org/#/c/trusted-firmware-m/+/2117/
https://review.trustedfirmware.org/c/trusted-firmware-m/+/2334/