make sure osmo-hnbgw re-connects dynamically
currently, when the MSC and/or SGSN are started after the HNBGW, the connections do not work.
One needs to wait for MSC,SGSN to start up and only then launch the HNBGW. That's really cumbersome.
(Also, the HNBGW does not fail when a connection did not succeed, so it has to be restarted manually)
Make HNBGW reconnect automatically.