sysfs: use SPDX identifiers

Move the license "mark" of the sysfs files to be in SPDX form, instead
of the custom text that it currently is in.  This is in a quest to get
rid of the 700+ different ways we say "GPLv2" in the kernel tree.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index 3f8efe8..4802ec0 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * fs/sysfs/group.c - Operations for adding/removing multiple files at once.
  *
@@ -5,9 +6,6 @@
  * Copyright (c) 2003 Open Source Development Lab
  * Copyright (c) 2013 Greg Kroah-Hartman
  * Copyright (c) 2013 The Linux Foundation
- *
- * This file is released undert the GPL v2.
- *
  */
 
 #include <linux/kobject.h>