samples: basic: blinky: s/gpio_is_ready_dt/gpio_get_dt

Use new API.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>

Author: gmarull

samples/basic/blinky/src/main.c

@@ -25,7 +25,7 @@ int main(void)
 	int ret;
 	bool led_state = true;
 
-	if (!gpio_is_ready_dt(&led)) {
+	if (gpio_get_dt(&led) < 0) {
 		return 0;
 	}