dt-bindings: usb: genesys,gl850g: add downstream facing ports

dt-bindings: usb: genesys,gl850g: add downstream facing ports

In order to describe connections between Genesys GL850G hub and
corresponding Type-C connectors, follow example of RTS5411 and describe
downstream facing ports. Unline normal case of ports being connected to
a USB device, hotplug ports use OF graph representation.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: "Rob Herring (Arm)" <robh@kernel.org>
Link: https://lore.kernel.org/r/20250608-genesys-ports-v1-2-09ca19f6838e@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>