dt-bindings: drm/panel: simple: add ortustech, com37h3m99dtc panel

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/3e0720fbddfd7b35ad8551440544411485d8ad9f.1559905870.git.hns@goldelico.com

Documentation/devicetree/bindings/display/panel/ortustech,com37h3m99dtc.txt

+OrtusTech COM37H3M99DTC Blanview 3.7" VGA portrait TFT-LCD panel
+
+Required properties:
+- compatible: should be "ortustech,com37h3m99dtc"
+
+Optional properties:
+- enable-gpios: GPIO pin to enable or disable the panel
+- backlight: phandle of the backlight device attached to the panel
+- power-supply: phandle of the regulator that provides the supply voltage
+
+This binding is compatible with the simple-panel binding, which is specified
+in simple-panel.txt in this directory.