dt-bindings: display: Add OSD Displays OSD070T1718-19TS panel binding

The OSD Displays OSD070T1718-19TS is a 7" WVGA (800x480) 24bit RGB panel
and is compatible with the simple-panel bindings.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

Documentation/devicetree/bindings/display/panel/osddisplays,osd070t1718-19ts.txt

+OSD Displays OSD070T1718-19TS 7" WVGA TFT LCD panel
+
+Required properties:
+- compatible: shall be "osddisplays,osd070t1718-19ts"
+- power-supply: see simple-panel.txt
+
+Optional properties:
+- backlight: see simple-panel.txt
+
+This binding is compatible with the simple-panel binding, which is specified
+in simple-panel.txt in this directory. No other simple-panel properties than
+the ones specified herein are valid.