ARM: dts: sun7i: Enable HDMI support on some A20 devices

All the A20 devices I own have standard HDMI connectors wired
to the dedicated HDMI pins on the SoC:

  - Bananapi M1+
  - Cubieboard 2
  - Cubietruck
  - Lamobo R1 (or Bananapi R1)

Development boards from Olimex also have standard HDMI connectors.
Schematics for them are publicly available. Enable HDMI on them as
well.

  - Olimex A20-OLinuXino-LIME
  - Olimex A20-OLinuXino-LIME2
  - Olimex A20-OLinuXino-MICRO

Enable the display pipeline and HDMI output for them.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Tested-by: Priit Laes <plaes@plaes.org> # Cubietruck, A20-OLinuXino-MICRO
Tested-by: Olliver Schinagl <oliver@schinagl.nl> # A20-OLinuXino-LIME2
Tested-by: Jonathan Liu <net147@gmail.com> # A20-OLinuXino-LIME
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>