Add trustzone application example

Add example project that builds both secure and nonsecure world
sides and the inference is done on the secure side.
This commit includes the mpc driver as found in the upstream
trustedfirmware git repository
https://git.trustedfirmware.org/TF-M/trusted-firmware-m.git
(8c0a234e453b51e6606d11599d0cb15097c3da48)

The model,input and output used are described in the README.md in this
directory.

Change-Id: Ie54904a38d54df4de2d6936f066c388ea58e396b