drivers: led_gpio: use `gpio_pin_set_dt`

Use the simpler version of `gpio_pin_set` to demonstrate usage.

Signed-off-by: Jordan Yates <jordan.yates@data61.csiro.au>
diff --git a/drivers/led/led_gpio.c b/drivers/led/led_gpio.c
index 25f3567..bd20193 100644
--- a/drivers/led/led_gpio.c
+++ b/drivers/led/led_gpio.c
@@ -36,7 +36,7 @@
 
 	led_gpio = &config->led[led];
 
-	return gpio_pin_set(led_gpio->port, led_gpio->pin, value > 0);
+	return gpio_pin_set_dt(led_gpio, value > 0);
 }
 
 static int led_gpio_on(const struct device *dev, uint32_t led)