trusty: add trusty-ipc driver

Trusty IPC driver provides message passing interface
between non-secure side (Linux) and secure side running
Trusty. It is handling a set of trusty IPC virtio devices
instantiated and configured by trusty-virtio driver based
on device description retrieved from secure side.

Change-Id: I81288aa458675996cbc93e73baf3c41d735d5429
Signed-off-by: Michael Ryleev <gmar@google.com>