components/safety_island: Add support for Inter SI communication

This patch will add support for Itnter Safety Island clusters
communication between cluster 0 and cluster 1.

Communication is based on the IPC RPMsg static vrings. Add virtual
ethernet driver on top of IPC to enable user applications to use BSD
sockets to communicate between clusters.

Signed-off-by: Rahul Singh <rahul.singh@arm.com>