Copter: use gps singleton for GCS function

ArduCopter/GCS_Mavlink.cpp

@@ -1769,11 +1769,6 @@ Compass *GCS_MAVLINK_Copter::get_compass() const
     return &copter.compass;
 }
 
-AP_GPS *GCS_MAVLINK_Copter::get_gps() const
-{
-    return &copter.gps;
-}
-
 AP_Camera *GCS_MAVLINK_Copter::get_camera() const
 {
 #if CAMERA == ENABLED

ArduCopter/GCS_Mavlink.h

@@ -23,7 +23,6 @@ protected:
     Compass *get_compass() const override;
     AP_Camera *get_camera() const override;
     AP_ServoRelayEvents *get_servorelayevents() const override;
-    AP_GPS *get_gps() const override;
     MAV_RESULT handle_flight_termination(const mavlink_command_long_t &packet) override;
     AP_AdvancedFailsafe *get_advanced_failsafe() const override;
     const AP_FWVersion &get_fwver() const override;