drm/panel: Add support for OTM8009A panel driver

This patch adds Orise Tech OTM8009A 3.97" 480x800 TFT LCD
panel driver (MIPI-DSI video mode). The panel backlight is
managed through the DSI link. This panel driver is used in
several STM32 boards.

Signed-off-by: Philippe CORNU <philippe.cornu@st.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1500297593-30633-4-git-send-email-philippe.cornu@st.com