iio: adc: ti-ads7950: use SPDX-License-Identifier

This updates the ti-ads7950.c file to use SPDX-License-Identifier
instead of more verbose license text.
Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ti-ads7950.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Texas Instruments ADS7950 SPI ADC driver
  *
@@ -10,15 +11,6 @@
  * And also on hwmon/ads79xx.c
  * Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com/
  *	Nishanth Menon
- *
- * 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.
  */
 
 #include <linux/acpi.h>