This is a GPIO driver so include only <linux/gpio/driver.h>.

Cc: kernel@savoirfairelinux.com
Cc: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Cc: Jerome Oufella <jerome.oufella@savoirfairelinux.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>