[PATCH] udev_volume_id: fix -d option

The -d option in udev_allows to go from a partition to the underlying disk
for s390 dasd labels. If the device is already the disk itself, finding the 
parent will fail, therefore -d on /sys/block/dasda/ for example gives no 
result at all.

extras/volume_id/udev_volume_id.c

@@ -186,7 +186,7 @@ int main(int argc, char *argv[])
 		if (class_dev_parent != NULL)
 			vid = open_classdev(class_dev_parent);
 		else
-			vid = open_classdev(class_dev_parent);
+			vid = open_classdev(class_dev);
 		if (vid == NULL)
 			goto exit;