dt-bindings: display: Add DT bindings for BOE HV070WSA-100 panel

The patch adds bindings to BOE HV070-WSA WSVGA panel. Bindings are
compatible with simple panel bindings.
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Maciej Purski <m.purski@samsung.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1529396370-18761-5-git-send-email-m.purski@samsung.com

Documentation/devicetree/bindings/display/panel/boe,hv070wsa-100.txt

+BOE HV070WSA-100 7.01" WSVGA TFT LCD panel
+
+Required properties:
+- compatible: should be "boe,hv070wsa-100"
+- power-supply: regulator to provide the VCC supply voltage (3.3 volts)
+- enable-gpios: GPIO pin to enable and disable panel (active high)
+
+This binding is compatible with the simple-panel binding, which is specified
+in simple-panel.txt in this directory.
+
+The device node can contain one 'port' child node with one child
+'endpoint' node, according to the bindings defined in [1]. This
+node should describe panel's video bus.
+
+[1]: Documentation/devicetree/bindings/media/video-interfaces.txt
+
+Example:
+
+	panel: panel {
+		compatible = "boe,hv070wsa-100";
+		power-supply = <&vcc_3v3_reg>;
+		enable-gpios = <&gpd1 3 GPIO_ACTIVE_HIGH>;
+		port {
+			panel_ep: endpoint {
+				remote-endpoint = <&bridge_out_ep>;
+			};
+		};
+	};