dt-bindings: usb: Convert Marvell Orion EHCI to DT schema

The Marvell Orion EHCI binding is just some compatible strings, so add it
to the generic-ehci.yaml schema.

Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230110-dt-usb-v3-4-5af0541fcf8c@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>