The code for setting MPU/PPC occupies much memory, try to refine them and reduce memory.
Patch link: https://review.trustedfirmware.org/#/c/trusted-firmware-m/+/1816/ https://review.trustedfirmware.org/#/c/trusted-firmware-m/+/1817/
https://review.trustedfirmware.org/#/c/trusted-firmware-m/+/1831/