dt-bindings: display: Add Sharp LS020B1DD01D panel documentation

The LS020B1DD01D is a 2.0" 240x160 16-bit TFT LCD panel.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190603153120.23947-1-paul@crapouillou.net

Documentation/devicetree/bindings/display/panel/sharp,ls020b1dd01d.txt

+Sharp 2.0" (240x160 pixels) 16-bit TFT LCD panel
+
+Required properties:
+- compatible: should be "sharp,ls020b1dd01d"
+- 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.