dt-bindings: usb: renesas,usb3-peri: Document HS and SS data bus

dt-bindings: usb: renesas,usb3-peri: Document HS and SS data bus

Document HS and SS data bus for the "usb-role-switch" enabled case.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200920134905.4370-4-biju.das.jz@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>