mtd: blkdevs: fix crash related to sysfs attributes.

Remove the attributes group before disk to avoid use after free

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index a6bb586..89e07e5 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -410,13 +410,14 @@
 		BUG();
 	}
 
-	/* Stop new requests to arrive */
-	del_gendisk(old->disk);
-
 	if (old->disk_attributes)
 		sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 						old->disk_attributes);
 
+	/* Stop new requests to arrive */
+	del_gendisk(old->disk);
+
+
 	/* Stop the thread */
 	kthread_stop(old->thread);