pinctrl: freescale: Switch to SPDX identifier

Adopt the SPDX license identifier headers to ease license compliance
management.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Reviewed-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/pinctrl/freescale/pinctrl-imx23.c b/drivers/pinctrl/freescale/pinctrl-imx23.c
index c940568..1440207 100644
--- a/drivers/pinctrl/freescale/pinctrl-imx23.c
+++ b/drivers/pinctrl/freescale/pinctrl-imx23.c
@@ -1,16 +1,9 @@
-/*
- * Freescale i.MX23 pinctrl driver
- *
- * Author: Shawn Guo <shawn.guo@linaro.org>
- * Copyright 2012 Freescale Semiconductor, Inc.
- *
- * The code contained herein is licensed under the GNU General Public
- * License. You may obtain a copy of the GNU General Public License
- * Version 2 or later at the following locations:
- *
- * http://www.opensource.org/licenses/gpl-license.html
- * http://www.gnu.org/copyleft/gpl.html
- */
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Freescale i.MX23 pinctrl driver
+//
+// Author: Shawn Guo <shawn.guo@linaro.org>
+// Copyright 2012 Freescale Semiconductor, Inc.
 
 #include <linux/init.h>
 #include <linux/of_device.h>