sandbox: led: use new function to configure default state

Initialize the led with the default state defined in device tree
in board_init and solve issue with test for led default state.

Reviewed-by: Simon Glass <sjg@chromium.org>

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>

test/dm/led.c

@@ -32,6 +32,9 @@ static int dm_test_led_default_state(struct unit_test_state *uts)
 {
 	struct udevice *dev;
 
+	/* configure the default state (auto-probe) */
+	led_default_state();
+
 	/* Check that we handle the default-state property correctly. */
 	ut_assertok(led_get_by_label("sandbox:default_on", &dev));
 	ut_asserteq(LEDST_ON, led_get_state(dev));