arm64: dts: imx8mn: remove otg1 power domain dependency on hsio

pgc_otg1 is an independent power domain of hsio, it's for usb phy,
so remove hsio power domain from its node.

Fixes: 8b8ebec6 ("arm64: dts: imx8mn: add GPC node")
Signed-off-by: Li Jun <jun.li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

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

@@ -662,7 +662,6 @@ pgc_hsiomix: power-domain@0 {
 					pgc_otg1: power-domain@1 {
 						#power-domain-cells = <0>;
 						reg = <IMX8MN_POWER_DOMAIN_OTG1>;
-						power-domains = <&pgc_hsiomix>;
 					};
 
 					pgc_gpumix: power-domain@2 {