pinctrl: amdisp: use new GPIO line value setter callbacks

struct gpio_chip now has callbacks for setting line values that return
an integer, allowing to indicate failures. Convert the driver to using
them.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://lore.kernel.org/20250612-gpiochip-set-rv-pinctrl-remaining-v1-16-556b0a530cd4@linaro.org


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>