tee: add sec_world_id to struct tee_shm

Adds sec_world_id to struct tee_shm which describes a shared memory
object. sec_world_id can be used by a driver to store an id assigned by
secure world.

Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>