Add device tree binding documentation for the Aspeed USB 2.0 Virtual HUb
Controller.
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NTao Ren <rentao.bupt@gmail.com>
Reviewed-by: NJoel Stanley <joel@jms.id.au>
Signed-off-by: NFelipe Balbi <balbi@kernel.org>