ARM: dts: sun8i: a83t: Enable HDMI output on Cubietruck Plus

The Cubietruck Plus has an HDMI connector tied to the HDMI output of the
SoC.

Enables display output via HDMI on the Cubietruck Plus. The connector
device node is named "hdmi-connector" as there is also a display port
connector, which is tied to the MIPI DSI output of the SoC through a
MIPI-DSI-to-DP bridge. This part is not supported yet.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>