Add TZ shim layer from NS side

RTOS defines an API to standardize the context memory system.
Implement a shim layer in the TZ API functions
to have the RTOS context manager call TF-M NSID API.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: I77327ae463ebb47579d406c510c071cfd5d31d1e
2 files changed