ARM: sunxi: dts: Add support for the cubieboard3, the CubieTruck

Cubietech introduced a new cubieboard, the CubieTruck. This board added
more output connectors and features 2 GiB of RAM and a Gigabit PHY.

Tested are are uart0 and LEDS which both work as expected.

Signed-off-by: Oliver Schinagl <oliver@schinagl.nl>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>