arm64: dts: imx8mp-dhcom-pdk3: Describe the USB-C connector

Describe the PTN5150 USB-C connector to improve the devicetree description
and fix the following dt-schema warning:

imx8mp-dhcom-pdk3.dtb: typec@3d: 'port' does not match any of the regexes: 'pinctrl-[0-9]+'
	from schema $id: http://devicetree.org/schemas/extcon/extcon-ptn5150.yaml#Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mp-dhcom-pdk3.dts

@@ -175,10 +175,14 @@ typec@3d {
 				pinctrl-names = "default";
 				pinctrl-0 = <&pinctrl_ptn5150>;
 
-				port {
-
-					ptn5150_out_ep: endpoint {
-						remote-endpoint = <&dwc3_0_ep>;
+				connector {
+					compatible = "usb-c-connector";
+					label = "USB-C";
+
+					port {
+						ptn5150_out_ep: endpoint {
+							remote-endpoint = <&dwc3_0_ep>;
+						};
 					};
 				};
 			};