dt-bindings: Add VXT VL050-8048NT-C01 panel bindings

The VXT VL050-8048NT-C01 is a TFT LCD panel with a 800x480 resolution
connected via 24 width parallel interface.
Reviewed-by: Otavio Salvador <otavio@ossystems.com.br>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190219002706.20077-2-festevam@gmail.com

Documentation/devicetree/bindings/display/panel/vl050_8048nt_c01.txt

+VXT 800x480 color TFT LCD panel
+
+Required properties:
+- compatible: should be "vxt,vl050-8048nt-c01"
+- power-supply: as specified in the base binding
+
+Optional properties:
+- backlight: as specified in the base binding
+- enable-gpios: as specified in the base binding
+
+This binding is compatible with the simple-panel binding, which is specified
+in simple-panel.txt in this directory.