dt-bindings: display: Add bindings for the LeMaker BL035-RGB-002 LCD panel

This adds the device-tree bindings for the LeMaker BL035-RGB-002 3.5"
QVGA TFT LCD panel, compatible with simple-panel.
Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181107181843.27628-6-contact@paulk.fr

Documentation/devicetree/bindings/display/panel/lemaker,bl035-rgb-002.txt

+LeMaker BL035-RGB-002 3.5" QVGA TFT LCD panel
+
+Required properties:
+- compatible: should be "lemaker,bl035-rgb-002"
+- 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.