drm/panel: simple: Add support for Banana Pi 7" S070WV20-CT16 panel

This panel is marketed as Banana Pi 7" LCD display. On the back is
a sticker denoting the model name S070WV20-CT16.

This is a 7" 800x480 panel connected through a 24-bit RGB interface.
However the panel only does 262k colors.

Depending on the variant, the PCB attached to the panel module either
supports DSI, or DSI + 24-bit RGB. DSI is converted to 24-bit RGB via
an onboard ICN6211 MIPI DSI - RGB bridge chip, then fed to the panel
itself.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180907041948.19913-5-wens@csie.org