ALSA: retain port-connections of slave devices

When the engine is re-started, ports should only be reconnected
when all slave devices are running. Previously those connections
were lost.

libs/backends/alsa/alsa_audiobackend.cc

@@ -982,7 +982,6 @@ AlsaAudioBackend::_start (bool for_latency_measurement)
 		return PortReconnectError;
 	}
 
-	engine.reconnect_ports ();
 	_run = true;
 	g_atomic_int_set (&_port_change_flag, 0);
 
@@ -1060,6 +1059,8 @@ AlsaAudioBackend::_start (bool for_latency_measurement)
 	}
 #endif
 
+	engine.reconnect_ports ();
+
 	return NoError;
 }