arm64: dts: imx8mp-phyboard-pollux: Enable USB support

Enable USB support for both interfaces in host mode.
USB1 is directly conncted to a type-A connector and USB2
is attached to a 4-Port USB Hub.

Signed-off-by: Teresa Remmet <t.remmet@phytec.de>
Signed-off-by: Cem Tenruh <c.tenruh@phytec.de>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>