Rover: remove unused update_navigation

APMrover2/APMrover2.cpp

@@ -408,9 +408,4 @@ void Rover::update_current_mode(void)
     control_mode->update();
 }
 
-void Rover::update_navigation()
-{
-    control_mode->update_navigation();
-}
-
 AP_HAL_MAIN_CALLBACKS(&rover);

APMrover2/Rover.h

@@ -431,7 +431,6 @@ private:
     void update_GPS_50Hz(void);
     void update_GPS_10Hz(void);
     void update_current_mode(void);
-    void update_navigation();
     void send_heartbeat(mavlink_channel_t chan);
     void send_attitude(mavlink_channel_t chan);
     void update_sensor_status_flags(void);

APMrover2/navigation.cpp

@@ -18,10 +18,6 @@ void Rover::navigate()
     // waypoint distance from rover
     // ----------------------------
     wp_distance = get_distance(current_loc, next_WP);
-
-    // control mode specific updates to nav_bearing
-    // --------------------------------------------
-    update_navigation();
 }