ARM: dts: rockchip: add the panel power supply for rk3288-evb board with act8846 pmu

Panel regulator is controller by a normal GPIO, so we need to
write a regulator-fixed node for it.
Signed-off-by: Yakir Yang <ykk@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm/boot/dts/rk3288-evb-act8846.dts

@@ -206,6 +206,10 @@ vcc18_lcd: REG12 {
 	};
 };
 
+&panel {
+	power-supply = <&vcc_lcd>;
+};
+
 &pinctrl {
 	lcd {
 		lcd_en: lcd-en  {