The Allwinner A10 and subsequent SoCs share the same display pipeline, with
variations in the number of controllers (1 or 2), or the presence or not of
some output (HDMI, TV, VGA) or not.

Add a driver with a limited set of features for now, and we will hopefully
support all of them eventually
Reviewed-by: NBoris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>