greybus: svc: destroy the route on module hot-unplug

We created two-way routes between the AP and module's interface on
hotplug, and forgot to remove them on hot-unplug. The same is also
required while handling errors in hotplug case.

Reviewed-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>