ARM: dts: sun7i: Enable USB DRC on Olimex A20 EVB

Enable the otg/drc usb controller on the Olimex A20 EVB.

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