ArduPlane: add CRUISE mode RC AUX Function switch

ArduPlane/RC_Channel.cpp

@@ -151,6 +151,7 @@ void RC_Channel_Plane::init_aux_function(const RC_Channel::aux_func_t ch_option,
     case AUX_FUNC::LANDING_FLARE:
     case AUX_FUNC::PARACHUTE_RELEASE:
     case AUX_FUNC::MODE_SWITCH_RESET:
+    case AUX_FUNC::CRUISE:
         break;
 
     case AUX_FUNC::Q_ASSIST:
@@ -316,6 +317,11 @@ case AUX_FUNC::ARSPD_CALIBRATE:
         plane.reset_control_switch();
         break;
 
+    case AUX_FUNC::CRUISE:
+        do_aux_function_change_mode(Mode::Number::CRUISE, ch_flag);
+        break;
+
+
     default:
         return RC_Channel::do_aux_function(ch_option, ch_flag);
     }