gpio: Use SPDX header for core library

Use the SPDX headers and cut down on boilerplate to indicate the
license in the core gpiolib implementation.

Signed-off-by: Linus Walleij <[e-mail]>

drivers/gpio/devres.c

···
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
- * drivers/gpio/devres.c - managed gpio resources
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2
- * as published by the Free Software Foundation.
- *
- * 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
- *
+ * devres.c - managed gpio resources
  * This file is based on kernel/irq/devres.c
  *
  * Copyright (c) 2011 John Crispin <[e-mail]>

drivers/gpio/gpio-mmio.c

···
+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Generic driver for memory-mapped GPIO controllers.
  *
  * Copyright 2008 MontaVista Software, Inc.
  * Copyright 2008,2010 Anton Vorontsov <[e-mail]>
- *
- * 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.
  *
  * ....``.```~~~~````.`.`.`.`.```````'',,,.........`````......`.......
  * ...``                                                         ```````..

drivers/gpio/gpiolib-acpi.c

···
+// SPDX-License-Identifier: GPL-2.0
 /*
  * ACPI helpers for GPIO API
  *
  * Copyright (C) 2012, Intel Corporation
  * Authors: Mathias Nyman <[e-mail]>
  *          Mika Westerberg <[e-mail]>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 
 #include <linux/errno.h>

drivers/gpio/gpiolib-devprop.c

···
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Device property helpers for GPIO chips.
  *
  * Copyright (C) 2016, Intel Corporation
  * Author: Mika Westerberg <[e-mail]>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 
 #include <linux/property.h>

drivers/gpio/gpiolib-legacy.c

···
+// SPDX-License-Identifier: GPL-2.0
 #include <linux/gpio/consumer.h>
 #include <linux/gpio/driver.h>
 

drivers/gpio/gpiolib-of.c

···
+// SPDX-License-Identifier: GPL-2.0
 /*
  * OF helpers for the GPIO API
  *
  * Copyright (c) 2007-2008  MontaVista Software, Inc.
  *
  * Author: Anton Vorontsov <[e-mail]>
- *
- * 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.
  */
 
 #include <linux/device.h>

drivers/gpio/gpiolib-sysfs.c

···
+// SPDX-License-Identifier: GPL-2.0
 #include <linux/idr.h>
 #include <linux/mutex.h>
 #include <linux/device.h>

drivers/gpio/gpiolib.c

···
+// SPDX-License-Identifier: GPL-2.0
 #include <linux/bitmap.h>
 #include <linux/kernel.h>
 #include <linux/module.h>

drivers/gpio/gpiolib.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Internal GPIO functions.
  *
  * Copyright (C) 2013, Intel Corporation
  * Author: Mika Westerberg <[e-mail]>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 
 #ifndef GPIOLIB_H