arm64: dts: rockchip: use just "port" in panel on RockPro64

The panel bindings expect to have only one port, thus they do not allow
to use "ports" node:

  rk3399-rockpro64.dtb: panel@0: 'ports' does not match any of the regexes: 'pinctrl-[0-9]+'

There is only one endpoint, so use simpler form without "reg".
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230326204520.80859-3-krzysztof.kozlowski@linaro.orgSigned-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3399-rockpro64.dtsi

@@ -647,19 +647,13 @@ mipi_panel: panel@0 {
 		avdd-supply = <&avdd>;
 		backlight = <&backlight>;
 		dvdd-supply = <&vcc3v3_s0>;
-		ports {
-			#address-cells = <1>;
-			#size-cells = <0>;
-
-			port@0 {
-				reg = <0>;
 
+		port {
 			mipi_in_panel: endpoint {
 				remote-endpoint = <&mipi_out_panel>;
 			};
 		};
 	};
-	};
 };
 
 &pcie0 {