drm/sun4i: Add compatible strings for the A80 display pipeline

This patch adds compatible strings for the remaining documented
components of the Allwinner A80 display pipeline.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180315114136.24747-5-wens@csie.org