dt-bindings: usb: Document the Microchip USB2514 hub

Document the Microchip USB2412, USB2417, and USB2514 USB hubs.

The existing usb251xb.yaml describes Microchip USB251x hubs that are
connected under I2C bus. Here, the hub is under the USB bus and use
the on-board-hub interface instead.

Signed-off-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20240405120147.880933-1-festevam@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>