GCS_MAVLink: Provide the time remaining

libraries/GCS_MAVLink/GCS_Common.cpp

@@ -280,6 +280,10 @@ void GCS_MAVLINK::send_battery_status(const uint8_t instance) const
     } else {
         consumed_wh = -1;
     }
+    uint32_t time_remaining;
+    if (!battery.time_remaining(time_remaining, instance)) {
+        time_remaining = 0;
+    }
 
     mavlink_msg_battery_status_send(chan,
                                     instance, // id
@@ -291,7 +295,7 @@ void GCS_MAVLINK::send_battery_status(const uint8_t instance) const
                                     consumed_mah, // total consumed current in milliampere.hour
                                     consumed_wh,  // consumed energy in hJ (hecto-Joules)
                                     percentage,
-                                    0, // time remaining, seconds (not provided)
+                                    time_remaining, // time remaining, seconds
                                     battery.get_mavlink_charge_state(instance), // battery charge state
                                     cell_volts_ext, // Cell 11..14 voltages
                                     0, // battery mode