dt-bindings: usb: mtu3: add support property role-switch-default-mode

Add support optional property of role-switch-default-mode,
used to set default mode while usb role is USB_ROLE_NONE when use
usb-role-switch to switch mode.

Acked-by: Rob Herring <[e-mail]>
Signed-off-by: Chunfeng Yun <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/devicetree/bindings/usb/mediatek,mtu3.yaml

···
     description: Support role switch.
     type: boolean
 
+  role-switch-default-mode:
+    enum: [host, peripheral]
+    default: host
+
   connector:
     $ref: /connector/usb-connector.yaml#
     description:
···
 dependencies:
   connector: [ 'usb-role-switch' ]
   port: [ 'usb-role-switch' ]
+  role-switch-default-mode: [ 'usb-role-switch' ]
   wakeup-source: [ 'mediatek,syscon-wakeup' ]
 
 required:
···
         wakeup-source;
         dr_mode = "otg";
         usb-role-switch;
+        role-switch-default-mode = "host";
         #address-cells = <1>;
         #size-cells = <1>;
         ranges;