dt-bindings: display: Add bindings for SGD GKTW70SDAE4SE Panel

The GKTW70SDAE4SE is an LVDS display panel.
Their bindings are modelled on the the LVDS panel bindings.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NNeil Armstrong <narmstrong@baylibre.com>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

Documentation/devicetree/bindings/display/panel/sgd,gktw70sdae4se.txt

+Solomon Goldentek Display GKTW70SDAE4SE LVDS Display Panel
+==========================================================
+
+The GKTW70SDAE4SE is a 7" WVGA TFT-LCD display panel.
+
+These DT bindings follow the LVDS panel bindings defined in panel-lvds.txt
+with the following device-specific properties.
+
+Required properties:
+
+- compatible: Shall contain "sgd,gktw70sdae4se" and "panel-lvds", in that order.
+
+Example
+-------
+
+panel {
+	compatible = "sgd,gktw70sdae4se", "panel-lvds";
+
+	width-mm = <153>;
+	height-mm = <86>;
+
+	data-mapping = "jeida-18";
+
+	panel-timing {
+		clock-frequency = <32000000>;
+		hactive = <800>;
+		vactive = <480>;
+		hback-porch = <39>;
+		hfront-porch = <39>;
+		vback-porch = <29>;
+		vfront-porch = <13>;
+		hsync-len = <47>;
+		vsync-len = <2>;
+	};
+
+	port {
+		panel_in: endpoint {
+			remote-endpoint = <&lvds_encoder>;
+		};
+	};
+};