USB: core: fix device node leak

Make sure to release any OF device-node reference taken when creating
the USB device.

Note that we currently do not hold a reference to the root hub
device-tree node (i.e. the parent controller node).

Fixes: 69bec7259853 ("USB: core: let USB device know device node")
Cc: stable <stable@vger.kernel.org>	# v4.6
Acked-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/usb.c

@@ -416,6 +416,8 @@ static void usb_release_dev(struct device *dev)
 
 	usb_destroy_configuration(udev);
 	usb_release_bos_descriptor(udev);
+	if (udev->parent)
+		of_node_put(dev->of_node);
 	usb_put_hcd(hcd);
 	kfree(udev->product);
 	kfree(udev->manufacturer);