mux: add SPDX identifiers to all mux source files

Remove all free-text license texts.

This is done on a quest to remove the 700+ different ways that files in
the kernel describe the GPL license text.

No copyright headers or other non-license-description text was removed.
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/mux/Kconfig

+# SPDX-License-Identifier: GPL-2.0
 #
 # Multiplexer devices
 #

drivers/mux/Makefile

+# SPDX-License-Identifier: GPL-2.0
 #
 # Makefile for multiplexer devices.
 #

drivers/mux/adg792a.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Multiplexer driver for Analog Devices ADG792A/G Triple 4:1 mux
  *
  * Copyright (C) 2017 Axentia Technologies AB
  *
  * Author: Peter Rosin <peda@axentia.se>
- *
- * 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/err.h>

drivers/mux/core.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Multiplexer subsystem
  *
  * Copyright (C) 2017 Axentia Technologies AB
  *
  * Author: Peter Rosin <peda@axentia.se>
- *
- * 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.
  */
 
 #define pr_fmt(fmt) "mux-core: " fmt

drivers/mux/gpio.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * GPIO-controlled multiplexer driver
  *
  * Copyright (C) 2017 Axentia Technologies AB
  *
  * Author: Peter Rosin <peda@axentia.se>
- *
- * 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/err.h>

drivers/mux/mmio.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * MMIO register bitfield-controlled multiplexer driver
  *
  * Copyright (C) 2017 Pengutronix, Philipp Zabel <kernel@pengutronix.de>
- *
- * 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/bitops.h>

include/linux/mux/consumer.h

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * mux/consumer.h - definitions for the multiplexer consumer interface
  *
  * Copyright (C) 2017 Axentia Technologies AB
  *
  * Author: Peter Rosin <peda@axentia.se>
- *
- * 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 _LINUX_MUX_CONSUMER_H

include/linux/mux/driver.h

+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * mux/driver.h - definitions for the multiplexer driver interface
  *
  * Copyright (C) 2017 Axentia Technologies AB
  *
  * Author: Peter Rosin <peda@axentia.se>
- *
- * 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 _LINUX_MUX_DRIVER_H