dt-bindings: extcon: ptn5150: add child node port

Add child node 'port' to allow connect to usb controller to do role-switch
if id pin of ptn5150 have not connected to chip's usb ID function pin.

Fix below warning:
arch/arm64/boot/dts/freescale/imx8mn-var-som-symphony.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

Link: https://lore.kernel.org/lkml/[email protected]/
Signed-off-by: Frank Li <[email protected]>
Reviewed-by: Krzysztof Kozlowski <[email protected]>
Signed-off-by: Chanwoo Choi <[email protected]>

Author: nxpfrankli

Documentation/devicetree/bindings/extcon/extcon-ptn5150.yaml

@@ -37,6 +37,11 @@ properties:
       GPIO pin (output) used to control VBUS. If skipped, no such control
       takes place.
 
+  port:
+    $ref: /schemas/graph.yaml#/properties/port
+    description:
+      A port node to link the usb controller for the dual role switch.
+
 required:
   - compatible
   - interrupts
@@ -58,5 +63,11 @@ examples:
             interrupt-parent = <&msmgpio>;
             interrupts = <78 IRQ_TYPE_LEVEL_HIGH>;
             vbus-gpios = <&msmgpio 148 GPIO_ACTIVE_HIGH>;
+
+            port {
+                endpoint {
+                    remote-endpoint = <&usb1_drd_sw>;
+                };
+            };
         };
     };