dt-bindings: display: simple: Add Satoz panel

Satoz is a Chinese TFT manufacturer.
Website: http://www.sat-sz.com/English/index.html



Add the compatible for its SAT050AT40H12R2 5.0 inch LCD panel.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200109184037.9091-1-miquel.raynal@bootlin.com