dt-bindings: usb: convert ti,hd3ss3220 bindings to json-schema

Convert ti,hd3ss3220.txt to YAML. Updated the binding documentation
as graph bindings of this device model Super Speed (SS) data bus to
the Super Speed (SS) capable connector.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20200920134905.4370-3-biju.das.jz@bp.renesas.com


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