ARM: dts: sun6i: Enable otg controller on the cs908

The cs908 has the otg controller connected to one of the 2 usb-A
receptacles it has on the front, so enable the otg controller in host-only
mode.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>