HITL: undefined time_remaining_s should be NAN

src/modules/mavlink/mavlink_receiver.cpp

@@ -2341,6 +2341,7 @@ MavlinkReceiver::handle_message_hil_sensor(mavlink_message_t *msg)
 		hil_battery_status.discharged_mah = -1.0f;
 		hil_battery_status.connected = true;
 		hil_battery_status.remaining = 0.70;
+		hil_battery_status.time_remaining_s = NAN;
 
 		_battery_pub.publish(hil_battery_status);
 	}
@@ -2770,6 +2771,7 @@ MavlinkReceiver::handle_message_hil_state_quaternion(mavlink_message_t *msg)
 		hil_battery_status.current_a = 10.0f;
 		hil_battery_status.discharged_mah = -1.0f;
 		hil_battery_status.timestamp = hrt_absolute_time();
+		hil_battery_status.time_remaining_s = NAN;
 		_battery_pub.publish(hil_battery_status);
 	}
 }