greybus: add a connection->private field

This will be used for driver-specific data for whatever drives the
other end of the connection.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/greybus/connection.h

@@ -25,6 +25,8 @@ struct gb_connection {
 
 	struct list_head		operations;
 	atomic_t			op_cycle;
+
+	void				*private;
 };
 
 struct gb_connection *gb_connection_create(struct gb_interface *interface,