platform/chrome: chromeos_laptop - add SPDX identifier

Replace the original license statement with the SPDX identifier.
Add also one line of description as recommended by the COPYING file.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Benson Leung <bleung@chromium.org>

drivers/platform/chrome/chromeos_laptop.c

-/*
- *  chromeos_laptop.c - Driver to instantiate Chromebook i2c/smbus devices.
- *
- *  Author : Benson Leung <bleung@chromium.org>
- *
- *  Copyright (C) 2012 Google, Inc.
- *
- *  This program is free software; you can redistribute it and/or modify
- *  it under the terms of the GNU General Public License as published by
- *  the Free Software Foundation; either version 2 of the License, or
- *  (at your option) any later version.
- *
- *  This program is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU General Public License for more details.
- *
- *  You should have received a copy of the GNU General Public License
- *  along with this program; if not, write to the Free Software
- *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
- *
- */
+// SPDX-License-Identifier: GPL-2.0+
+// Driver to instantiate Chromebook i2c/smbus devices.
+//
+// Copyright (C) 2012 Google, Inc.
+// Author: Benson Leung <bleung@chromium.org>
 
 #include <linux/dmi.h>
 #include <linux/i2c.h>