dt-bindings: usb: dwc3-imx8mp: add power domain property

The USB controllers in the i.MX8MP are located inside the HSIO
power domain. Add the power-domains property to the DT binding
to be able to describe the hardware properly.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230110180804.594462-1-l.stach@pengutronix.de


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