subscr: Kick the queue in case of a paging timeout

Kick the queue in case the paging was timing out. No one is going
to call subscr_put_channel for us so we will do it on the subscriber.

There is also another problem with multiple BTS in the LAC and paging
timeout. We will need to remember how many BTSes we have paged.

openbsc/src/gsm_subscriber.c

@@ -103,6 +103,9 @@ static int subscr_paging_dispatch(unsigned int hooknum, unsigned int event,
 	request->cbfn(hooknum, event, msg, data, request->param);
 	subscr->in_callback = 0;
 
+	if (event != GSM_PAGING_SUCCEEDED)
+		subscr_put_channel(subscr);
+
 	subscr_put(subscr);
 	talloc_free(request);
 	return 0;