iio: adc: nau7802: Make use of device properties

Convert the module to be property provider agnostic and allow
it to be used on non-OF platforms.

Add mod_devicetable.h include.

Signed-off-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/adc/nau7802.c

···
 #include <linux/delay.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
+#include <linux/mod_devicetable.h>
 #include <linux/module.h>
+#include <linux/property.h>
 #include <linux/wait.h>
 #include <linux/log2.h>
-#include <linux/of.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
···
 {
 	struct iio_dev *indio_dev;
 	struct nau7802_state *st;
-	struct device_node *np = client->dev.of_node;
 	int i, ret;
 	u8 data;
 	u32 tmp = 0;
···
 	if (!(ret & NAU7802_PUCTRL_PUR_BIT))
 		return ret;
 
-	of_property_read_u32(np, "nuvoton,vldo", &tmp);
+	device_property_read_u32(&client->dev, "nuvoton,vldo", &tmp);
 	st->vref_mv = tmp;
 
 	data = NAU7802_PUCTRL_PUD_BIT | NAU7802_PUCTRL_PUA_BIT |