pinctrl: renesas: rzg2l: Use new GPIO line value setter callbacks

pinctrl: renesas: rzg2l: 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>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250611-gpiochip-set-rv-pinctrl-renesas-v1-2-ad169a794ef0@linaro.org
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>