bindings: usb: dwc3: Update dwc3 properties for EUD connector

Add the ports property for dwc3 node. This port can be used
by the Embedded USB Debugger for role switching the controller
from device to host mode and vice versa.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Souradeep Chowdhury <quic_schowdhu@quicinc.com>
Link: https://lore.kernel.org/r/7308170ce13a96c2ff9cbb22316f46c814c42ef1.1644339918.git.quic_schowdhu@quicinc.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/snps,dwc3.yaml

@@ -335,6 +335,12 @@ properties:
     items:
       enum: [1, 4, 8, 16, 32, 64, 128, 256]
 
+  port:
+    $ref: /schemas/graph.yaml#/properties/port
+    description:
+      This port is used with the 'usb-role-switch' property  to connect the
+      dwc3 to type C connector.
+
 unevaluatedProperties: false
 
 required: