arm64: dts: imx8mm: remove otg1/2 power domain dependency on hsio

pgc_otg1/2 are independent power domain of hsio, they for usb phy,
so remove hsio power domain dependency from its node.

Fixes: d39d4bb1 ("arm64: dts: imx8mm: add GPC node")
Signed-off-by: Li Jun <jun.li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>