dt-bindings: usb: generic-ehci: document spurious-oc flag

Over-current reporting isn't supported on some platforms such as bcm63xx.
These devices will incorrectly report over-current if this flag isn't properly
activated.
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20210223174455.1378-3-noltari@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/generic-ehci.yaml

@@ -122,6 +122,12 @@ properties:
     description:
       Set this flag to force EHCI reset after resume.
 
+  spurious-oc:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description:
+      Set this flag to indicate that the hardware sometimes turns on
+      the OC bit when an over-current isn't actually present.
+
   companion:
     $ref: /schemas/types.yaml#/definitions/phandle
     description: