Rover: allow base class to set_control_channels in initialisation

APMrover2/Rover.h

@@ -350,7 +350,7 @@ private:
     void load_parameters(void) override;
 
     // radio.cpp
-    void set_control_channels(void);
+    void set_control_channels(void) override;
     void init_rc_in();
     void rudder_arm_disarm_check();
     void read_radio();

APMrover2/system.cpp

@@ -86,7 +86,6 @@ void Rover::init_ardupilot()
 
     ins.set_log_raw_bit(MASK_LOG_IMU_RAW);
 
-    set_control_channels();  // setup radio channels and outputs ranges
     init_rc_in();            // sets up rc channels deadzone
     g2.motors.init();        // init motors including setting servo out channels ranges
     SRV_Channels::enable_aux_servos();