iio: as3935: Drop GPIO includes

The driver includes <linux/gpio.h> and <linux/of_gpio.h> yet
fails to use symbols from any of the include files, so drop
these includes.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/proximity/as3935.c

@@ -14,7 +14,6 @@
 #include <linux/mutex.h>
 #include <linux/err.h>
 #include <linux/irq.h>
-#include <linux/gpio.h>
 #include <linux/spi/spi.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
@@ -22,8 +21,6 @@
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/buffer.h>
 #include <linux/iio/triggered_buffer.h>
-#include <linux/of_gpio.h>
-
 
 #define AS3935_AFE_GAIN		0x00
 #define AS3935_AFE_MASK		0x3F