pinctrl: bcm-iproc: Use SPDX header

This convert the BCM IPROC driver to use the SPDX header
for indicating GPL v2.0 only licensing.

Cc: Pramod Kumar <pramodku@broadcom.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20191002130217.4491-1-linus.walleij@linaro.org

drivers/pinctrl/bcm/pinctrl-iproc-gpio.c

+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2014-2017 Broadcom
- *
- * 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 version 2.
- *
- * This program is distributed "as is" WITHOUT ANY WARRANTY of any
- * kind, whether express or implied; without even the implied warranty
- * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
  */
 
 /*