leds: leds-gpio: Fix the "default-state" property check

Commit a43f2cbbb009f9 ("leds: leds-gpio: Make use of device property API")
caused a regression by reading the incorrect string for the "default-state"
property.

Fix the property string check to restore the original behaviour.

Fixes: a43f2cbbb009 (leds: leds-gpio: Make use of device property API)
Reported-by: Jean-Michel Hautbois <jean-michel.hautbois@vodalys.com>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Bryan Wu <cooloney@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/leds/leds-gpio.c

@@ -203,7 +203,7 @@ static struct gpio_leds_priv *gpio_leds_create(struct platform_device *pdev)
 		fwnode_property_read_string(child, "linux,default-trigger",
 					    &led.default_trigger);
 
-		if (!fwnode_property_read_string(child, "linux,default_state",
+		if (!fwnode_property_read_string(child, "default-state",
 						 &state)) {
 			if (!strcmp(state, "keep"))
 				led.default_state = LEDS_GPIO_DEFSTATE_KEEP;