greybus: ap: add svc_set_route_send() command and use it on a link up event

greybus: ap: add svc_set_route_send() command and use it on a link up event

When the AP receives a link up event, request that the SVC set a
route to the interface's device id (this device id has been
previously reported to the AP). In the future, we may not always
immediately set a route upon receiving a link up event but this
is sufficient for the known use cases at this time.

Signed-off-by: Matt Porter <mporter@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>