wayland: Don't deduce layer shell window layer based on window type

It seemed like a good idea at the time, but it conflicts with the client
side wishing to change the layer.

src/layershellv1window.cpp

@@ -193,9 +193,6 @@ void LayerShellV1Window::closeWindow()
 
 Layer LayerShellV1Window::belongsToLayer() const
 {
-    if (!isNormalWindow()) {
-        return WaylandWindow::belongsToLayer();
-    }
     switch (m_shellSurface->layer()) {
     case LayerSurfaceV1Interface::BackgroundLayer:
         return DesktopLayer;