dt-bindings: usb: renesas-xhci: Refer to the usb-xhci.yaml file

dt-bindings: usb: renesas-xhci: Refer to the usb-xhci.yaml file

With minor peculiarities (like uploading some vendor-specific firmware)
these are just Generic xHCI controllers fully compatible with its
properties. Make sure the Renesas USB xHCI DT nodes are also validated
against the Generic xHCI DT schema.

Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201210090944.16283-10-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>