ARM: dts: exynos: add panel supply in Tiny4412

The simple panel should have a supply.  Provide a stub, as the board DTS
does not have a PMIC node, to silence warning:

  exynos4412-tiny4412.dtb: panel: 'power-supply' is a required property

Link: https://lore.kernel.org/r/20230120155404.323386-7-krzysztof.kozlowski@linaro.orgSigned-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

arch/arm/boot/dts/exynos4412-tiny4412.dts

@@ -79,6 +79,7 @@ pmic_ap_clk: pmic-ap-clk {
 
 	panel {
 		compatible = "innolux,at070tn92";
+		power-supply = <&vddq_lcd>;
 
 		port {
 			panel_input: endpoint {
@@ -86,6 +87,13 @@ panel_input: endpoint {
 			};
 		};
 	};
+
+	vddq_lcd: regulator-vddq-lcd {
+		compatible = "regulator-fixed";
+		regulator-name = "vddq-lcd";
+		regulator-min-microvolt = <1800000>;
+		regulator-max-microvolt = <1800000>;
+	};
 };
 
 &cpu_thermal {