wayland: Fix handling of exclusive zone of -1

We cannot use Workspace::clientArea() to get the geometry of the screen
as the clientArea() method needs a valid frame geometry. This is not the
case if the layer shell surface is being configured for the first time.

src/layershellv1integration.cpp

@@ -103,7 +103,7 @@ static void rearrangeLayer(const QList<LayerShellV1Client *> &clients, QRect *wo
 
         QRect bounds;
         if (shellSurface->exclusiveZone() == -1) {
-            bounds = workspace()->clientArea(ScreenArea, client);
+            bounds = client->output()->geometry();
         } else {
             bounds = *workArea;
         }