USB: appledisplay: Deletion of a check before backlight_device_unregister()

The backlight_device_unregister() function tests whether its argument is NULL
and then returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/misc/appledisplay.c

@@ -329,7 +329,7 @@ static int appledisplay_probe(struct usb_interface *iface,
 					pdata->urbdata, pdata->urb->transfer_dma);
 			usb_free_urb(pdata->urb);
 		}
-		if (pdata->bd && !IS_ERR(pdata->bd))
+		if (!IS_ERR(pdata->bd))
 			backlight_device_unregister(pdata->bd);
 		kfree(pdata->msgdata);
 	}