ARM: dts: sun5i: q8-tablet: Add LCD Panel enable GPIO

Now that we support the AXP209 GPIOs, we can toggle the LCD panel enable
line. Add the GPIO phandle to the panel.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>

arch/arm/boot/dts/sun5i-a13-q8-tablet.dts

@@ -50,7 +50,7 @@ / {
 
 	panel: panel {
 		compatible = "urt,umsh-8596md-t", "simple-panel";
-		/* TODO: lcd panel uses axp gpio0 as enable pin */
+		enable-gpios = <&axp_gpio 0 GPIO_ACTIVE_HIGH>; /* AXP GPIO0 */
 		backlight = <&backlight>;
 		#address-cells = <1>;
 		#size-cells = <0>;