dt-bindings: usb: usb-drd: Add "otg-rev" property constraints

There are only four OTG revisions are currently supported by the kernel:
0x0100, 0x0120, 0x0130, 0x0200. Any another value is considered as
invalid.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201210090944.16283-4-Sergey.Semin@baikalelectronics.ruSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/usb-drd.yaml

@@ -18,6 +18,7 @@ properties:
       features (HNP/SRP/ADP) is enabled. If ADP is required, otg-rev should be
       0x0200 or above.
     $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [0x0100, 0x0120, 0x0130, 0x0200]
 
   dr_mode:
     description: