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>
diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
index 19e4e90..6241678 100644
--- a/drivers/mux/Kconfig
+++ b/drivers/mux/Kconfig
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 #
 # Multiplexer devices
 #
diff --git a/drivers/mux/Makefile b/drivers/mux/Makefile
index 0e1e597..c3d8839 100644
--- a/drivers/mux/Makefile
+++ b/drivers/mux/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 #
 # Makefile for multiplexer devices.
 #
diff --git a/drivers/mux/adg792a.c b/drivers/mux/adg792a.c
index 12aa221..6a8725cf 100644
--- a/drivers/mux/adg792a.c
+++ b/drivers/mux/adg792a.c
@@ -1,13 +1,10 @@
+// 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>
diff --git a/drivers/mux/core.c b/drivers/mux/core.c
index 2260063..959d22a 100644
--- a/drivers/mux/core.c
+++ b/drivers/mux/core.c
@@ -1,13 +1,10 @@
+// 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
diff --git a/drivers/mux/gpio.c b/drivers/mux/gpio.c
index 468bf17..6fdd9316 100644
--- a/drivers/mux/gpio.c
+++ b/drivers/mux/gpio.c
@@ -1,13 +1,10 @@
+// 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>
diff --git a/drivers/mux/mmio.c b/drivers/mux/mmio.c
index 37c1de3..935ac44a 100644
--- a/drivers/mux/mmio.c
+++ b/drivers/mux/mmio.c
@@ -1,11 +1,8 @@
+// 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>
diff --git a/include/linux/mux/consumer.h b/include/linux/mux/consumer.h
index ea96d4c..5fc6bb2 100644
--- a/include/linux/mux/consumer.h
+++ b/include/linux/mux/consumer.h
@@ -1,13 +1,10 @@
+/* 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
diff --git a/include/linux/mux/driver.h b/include/linux/mux/driver.h
index 35c3579..627a2c6 100644
--- a/include/linux/mux/driver.h
+++ b/include/linux/mux/driver.h
@@ -1,13 +1,10 @@
+/* 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