arm64: dts: imx8mn: put USB controller into power-domains

Now that we have support for the power domain controller on the i.MX8MN,
we can put the USB controller in the respective power domain to allow
it to power down the PHY when possible.
Signed-off-by: NAdam Ford <aford173@gmail.com>
Reviewed-by: NLucas Stach <l.stach@pengutronix.de>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mn.dtsi

@@ -1048,6 +1048,7 @@
 				assigned-clock-parents = <&clk IMX8MN_SYS_PLL2_500M>;
 				phys = <&usbphynop1>;
 				fsl,usbmisc = <&usbmisc1 0>;
+				power-domains = <&pgc_otg1>;
 				status = "disabled";
 			};