iio: itg3200: Drop GPIO include

The driver include <linux/gpio.h> yet does not use any
of the symbols from the header, so drop the include.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/gyro/itg3200_core.c

@@ -15,7 +15,6 @@
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/i2c.h>
-#include <linux/gpio.h>
 #include <linux/slab.h>
 #include <linux/stat.h>
 #include <linux/module.h>