dt-bindings: phy: imx8mq-usb: add power-domains property

Add optional power-domains property for usb phy.
Signed-off-by: NPeng Fan <peng.fan@nxp.com>
Acked-by: NAlexander Stein <alexander.stein@ew.tq-group.com>
Acked-by: NRob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20221014095550.2125018-1-peng.fan@oss.nxp.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/phy/fsl,imx8mq-usb-phy.yaml

@@ -28,6 +28,9 @@ properties:
     items:
       - const: phy
 
+  power-domains:
+    maxItems: 1
+
   vbus-supply:
     description:
       A phandle to the regulator for USB VBUS.