iio: dac: ad7303: remove platform data header

The information in the ad7303 platform_data header is unused, so it's dead
code.
This change removes it and it's inclusion from the driver.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20201001141004.53846-1-alexandru.ardelean@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/dac/ad7303.c

@@ -17,8 +17,6 @@
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 
-#include <linux/platform_data/ad7303.h>
-
 #define AD7303_CFG_EXTERNAL_VREF BIT(15)
 #define AD7303_CFG_POWER_DOWN(ch) BIT(11 + (ch))
 #define AD7303_CFG_ADDR_OFFSET	10

include/linux/platform_data/ad7303.h

-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Analog Devices AD7303 DAC driver
- *
- * Copyright 2013 Analog Devices Inc.
- */
-
-#ifndef __IIO_ADC_AD7303_H__
-#define __IIO_ADC_AD7303_H__
-
-/**
- * struct ad7303_platform_data - AD7303 platform data
- * @use_external_ref: If set to true use an external voltage reference connected
- * to the REF pin, otherwise use the internal reference derived from Vdd.
- */
-struct ad7303_platform_data {
-	bool use_external_ref;
-};
-
-#endif