drm/i915/overlay: Destroy reg_bo on shutdown.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_overlay.c

@@ -1461,14 +1461,16 @@ void intel_cleanup_overlay(struct drm_device *dev)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
 
-	if (dev_priv->overlay) {
+	if (!dev_priv->overlay)
+		return;
+
 	/* The bo's should be free'd by the generic code already.
 	 * Furthermore modesetting teardown happens beforehand so the
 	 * hardware should be off already */
 	BUG_ON(dev_priv->overlay->active);
 
+	drm_gem_object_unreference_unlocked(&dev_priv->overlay->reg_bo->base);
 	kfree(dev_priv->overlay);
-	}
 }
 
 struct intel_overlay_error_state {