drm/panel: simple: Add support for KEO TX31D200VM0BAA

This adds support for the Kaohsiung Opto-Electronics.,
TX31D200VM0BAA 12.3" HSXGA LVDS panel, which can be
supported by the simple panel driver.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1517766571-409-5-git-send-email-jagan@amarulasolutions.com