Copter: stop passing gcs chan into method which wants an object

ArduCopter/Copter.h

@@ -670,7 +670,7 @@ private:
     bool far_from_EKF_origin(const Location& loc);
 
     // compassmot.cpp
-    MAV_RESULT mavlink_compassmot(mavlink_channel_t chan);
+    MAV_RESULT mavlink_compassmot(const GCS_MAVLINK &gcs_chan);
 
     // crash_check.cpp
     void crash_check();

ArduCopter/GCS_Mavlink.cpp

@@ -539,7 +539,7 @@ MAV_RESULT GCS_MAVLINK_Copter::_handle_command_preflight_calibration(const mavli
 {
     if (is_equal(packet.param6,1.0f)) {
         // compassmot calibration
-        return copter.mavlink_compassmot(chan);
+        return copter.mavlink_compassmot(*this);
     }
 
     return GCS_MAVLINK::_handle_command_preflight_calibration(packet);

ArduCopter/compassmot.cpp

@@ -5,7 +5,7 @@
  */
 
 // setup_compassmot - sets compass's motor interference parameters
-MAV_RESULT Copter::mavlink_compassmot(mavlink_channel_t chan)
+MAV_RESULT Copter::mavlink_compassmot(const GCS_MAVLINK &gcs_chan)
 {
 #if FRAME_CONFIG == HELI_FRAME
     // compassmot not implemented for tradheli
@@ -33,8 +33,6 @@ MAV_RESULT Copter::mavlink_compassmot(mavlink_channel_t chan)
         ap.compass_mot = true;
     }
 
-    GCS_MAVLINK_Copter &gcs_chan = gcs().chan(chan-MAVLINK_COMM_0);
-
     // check compass is enabled
     if (!AP::compass().enabled()) {
         gcs_chan.send_text(MAV_SEVERITY_CRITICAL, "Compass disabled");
@@ -85,7 +83,7 @@ MAV_RESULT Copter::mavlink_compassmot(mavlink_channel_t chan)
     }
 
     // send back initial ACK
-    mavlink_msg_command_ack_send(chan, MAV_CMD_PREFLIGHT_CALIBRATION,0);
+    mavlink_msg_command_ack_send(gcs_chan.get_chan(), MAV_CMD_PREFLIGHT_CALIBRATION,0);
 
     // flash leds
     AP_Notify::flags.esc_calibration = true;
@@ -215,7 +213,7 @@ MAV_RESULT Copter::mavlink_compassmot(mavlink_channel_t chan)
 
         if (AP_HAL::millis() - last_send_time > 500) {
             last_send_time = AP_HAL::millis();
-            mavlink_msg_compassmot_status_send(chan, 
+            mavlink_msg_compassmot_status_send(gcs_chan.get_chan(),
                                                channel_throttle->get_control_in(),
                                                battery.current_amps(),
                                                interference_pct[compass.get_primary()],