ARM: dts: sun7i: Enable HDMI on pcDuino3 Nano

The board has a regular-sized HDMI connector, so enable the display
the pipeline and HDMI output for it.

Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>