Copter: add pad fields for extended COMMAND_ACK

ArduCopter/compassmot.cpp

@@ -85,7 +85,8 @@ MAV_RESULT Copter::mavlink_compassmot(const GCS_MAVLINK &gcs_chan)
     }
 
     // send back initial ACK
-    mavlink_msg_command_ack_send(gcs_chan.get_chan(), MAV_CMD_PREFLIGHT_CALIBRATION,0);
+    mavlink_msg_command_ack_send(gcs_chan.get_chan(), MAV_CMD_PREFLIGHT_CALIBRATION,0,
+                                 0, 0, 0, 0);
 
     // flash leds
     AP_Notify::flags.esc_calibration = true;