init adjustments to ensure used topics are advertised early (primarily for logging)

- multi-EKF create each instance as soon as IMU & mag are advertised (before device id populated)

src/lib/mixer_module/mixer_module.cpp

@@ -103,6 +103,9 @@ _param_prefix(param_prefix)
 		}
 
 		updateParams();
+
+	} else {
+		_control_allocator_status_pub.advertise();
 	}
 
 	_outputs_pub.advertise();