soc: imx: gpcv2: add GENPD_FLAG_ACTIVE_WAKEUP flag for usb of imx8mm/n

To keep the power domain on if usb remote wakeup is enabled, add the
GENPD_FLAG_ACTIVE_WAKEUP for otg1/2 of imx8mm/n.

Signed-off-by: Li Jun <jun.li@nxp.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>