return value is an error or a cookie identifying this overlay.
2. Call of_overlay_remove() to remove and cleanup the overlay changeset
-previously created via the call to of_overlay_apply(). Removal of an overlay
-changeset that is stacked by another will not be permitted.
+previously created via the call to of_overlay_fdt_apply(). Removal of an
+overlay changeset that is stacked by another will not be permitted.
Finally, if you need to remove all overlays in one-go, just call
of_overlay_remove_all() which will remove every single one in the correct