arm64: dts: imx8mn: Correct the usb power domain

pgc_otg1 is actual the power domain of usb PHY, usb controller
is in hsio power domain, and pgc_otg1 is required to be powered
up to detect usb remote wakeup, so move the pgc_otg1 power domain
to the usb phy node.

Fixes: ea2b5af5 ("arm64: dts: imx8mn: put USB controller into power-domains")
Signed-off-by: Li Jun <jun.li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>