Vehicle: Fix joystick enabled state checkbox

src/Vehicle/Vehicle.cc

@@ -838,6 +838,7 @@ void Vehicle::setJoystickEnabled(bool enabled)
     _joystickEnabled = enabled;
     _startJoystick(_joystickEnabled);
     _saveSettings();
+    emit joystickEnabledChanged(_joystickEnabled);
 }
 
 void Vehicle::_startJoystick(bool start)

src/VehicleSetup/JoystickConfig.qml

@@ -355,12 +355,10 @@ QGCView {
 
 
                         QGCCheckBox {
-                            enabled:    allowEnableDisable
+                            enabled:    _activeJoystick.calibrated
                             text:       _activeJoystick.calibrated ? "Enable joystick input" : "Enable/Disable not allowed (Calibrate First)"
                             checked:    _activeVehicle.joystickEnabled
 
-                            property bool allowEnableDisable:   _activeJoystick.calibrated
-
                             onClicked:  _activeVehicle.joystickEnabled = checked
                         }