Add support for the VXT VL050-8048NT-C01 800x480 panel to the
panel-simple driver.

This panel is used on some boards manufactured by TechNexion, such as
imx7d-pico.

Reviewed-by: Otavio Salvador <otavio@ossystems.com.br>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190219002706.20077-3-festevam@gmail.com