leds: lgm-sso: 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: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250423-gpiochip-set-rv-leds-v1-1-2f42d8fbb525@linaro.org
Signed-off-by: Lee Jones <lee@kernel.org>

Author: Bartosz Golaszewski

drivers/leds/blink/leds-lgm-sso.c

@@ -450,14 +450,16 @@ static int sso_gpio_get(struct gpio_chip *chip, unsigned int offset)
 	return !!(reg_val & BIT(offset));
 }
 
-static void sso_gpio_set(struct gpio_chip *chip, unsigned int offset, int value)
+static int sso_gpio_set(struct gpio_chip *chip, unsigned int offset, int value)
 {
 	struct sso_led_priv *priv = gpiochip_get_data(chip);
 
 	regmap_update_bits(priv->mmap, SSO_CPU, BIT(offset), value << offset);
 	if (!priv->gpio.freq)
 		regmap_update_bits(priv->mmap, SSO_CON0, SSO_CON0_SWU,
 				   SSO_CON0_SWU);
+
+	return 0;
 }
 
 static int sso_gpio_gc_init(struct device *dev, struct sso_led_priv *priv)
@@ -469,7 +471,7 @@ static int sso_gpio_gc_init(struct device *dev, struct sso_led_priv *priv)
 	gc->get_direction       = sso_gpio_get_dir;
 	gc->direction_output    = sso_gpio_dir_out;
 	gc->get                 = sso_gpio_get;
-	gc->set                 = sso_gpio_set;
+	gc->set_rv              = sso_gpio_set;
 
 	gc->label               = "lgm-sso";
 	gc->base                = -1;