station: Return NotHidden error

Commit d372d59bea checks whether a hidden network had a previous
connection attempt and re-tries.  However, it inadvertently dropped
handling of a condition where a non-hidden network SSID is provided to
ConnectHiddenNetwork.  Fix that.

Fixes: d372d59bea ("station: Allow ConnectHiddenNetwork to be retried")

src/station.c

@@ -2722,6 +2722,8 @@ static struct l_dbus_message *station_dbus_connect_hidden_network(
 			return network_connect_new_hidden_network(network,
 								message);
 		}
+
+		return dbus_error_not_hidden(message);
 	}
 
 	params.ssid = ssid;