The driver already includes <linux/gpio/consumer.h> which is what
it uses, drop the legacy <linux/gpio.h> include.

Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>