ARM: dts: stm32: Add power-supply for RGB panel on stm32429i-eval

Add a fixed regulator and use it as power supply for RBG panel.
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32429i-eval.dts

@@ -95,6 +95,13 @@ vref: regulator-vref {
 		regulator-max-microvolt = <3300000>;
 	};
 
+	vdd_panel: vdd-panel {
+		compatible = "regulator-fixed";
+		regulator-name = "vdd_panel";
+		regulator-min-microvolt = <3300000>;
+		regulator-max-microvolt = <3300000>;
+	};
+
 	leds {
 		compatible = "gpio-leds";
 		green {
@@ -138,6 +145,7 @@ usbotg_hs_phy: usbphy {
 
 	panel_rgb: panel-rgb {
 		compatible = "ampire,am-480272h3tmqw-t01h";
+		power-supply = <&vdd_panel>;
 		status = "okay";
 		port {
 			panel_in_rgb: endpoint {