ARM: dts: sun5i: Add simplefb node for tvencoder output

Add a simplefb node for tvencoder / composite-video output, such as found
on the Auxtek-T003 and the CHIP.

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