sunxi: Display: Add support for eDP panels connected via an anx9804 bridge

Add support for 4 1.62G lane eDP panels connected via an anx9804 bridge,
such as found on the Colombus devkit.

While at it also fix the wrong indentation of the SSD2828 Kconfig help text
in board/sunxi/Kconfig.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>