gpio: max730x: Use the right include

<linux/spi/max7301.h> despite the placement of the header, is
used by drivers/gpio/gpio-max730*.

The include needs struct gpio_chip and needs to include
<linux/gpio/driver.h> not the legacy <linux/gpio.h> include.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>