Plane: stop setting terrain singleton; libraries use singleton

ArduPlane/quadplane.cpp

@@ -790,9 +790,6 @@ bool QuadPlane::setup(void)
         AP_BoardConfig::config_error("Unable to allocate %s", "wp_nav");
     }
     AP_Param::load_object_from_eeprom(wp_nav, wp_nav->var_info);
-#if AP_TERRAIN_AVAILABLE
-    wp_nav->set_terrain(&plane.terrain);
-#endif
 
     loiter_nav = new AC_Loiter(inertial_nav, *ahrs_view, *pos_control, *attitude_control);
     if (!loiter_nav) {

ArduPlane/system.cpp

@@ -146,11 +146,6 @@ void Plane::init_ardupilot()
 #if AC_FENCE == ENABLED
     fence.init();
 #endif
-
-#if AP_TERRAIN_AVAILABLE
-    Location::set_terrain(&terrain);
-#endif
-
 }
 
 //********************************************************************************