dt-bindings: display/panel: Add KOE tx14d24vm1bpa display description

This commit adds documentation entry description for KOE's 5.7" display.
Signed-off-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190515160428.6114-1-lukma@denx.de

Documentation/devicetree/bindings/display/panel/koe,tx14d24vm1bpa.txt

+Kaohsiung Opto-Electronics Inc. 5.7" QVGA (320 x 240) TFT LCD panel
+
+Required properties:
+- compatible: should be "koe,tx14d24vm1bpa"
+- backlight: phandle of the backlight device attached to the panel
+- power-supply: single regulator to provide the supply voltage
+
+Required nodes:
+- port: Parallel port mapping to connect this display
+
+This panel needs single power supply voltage. Its backlight is conntrolled
+via PWM signal.
+
+Example:
+--------
+
+Example device-tree definition when connected to iMX53 based board
+
+	lcd_panel: lcd-panel {
+		compatible = "koe,tx14d24vm1bpa";
+		backlight = <&backlight_lcd>;
+		power-supply = <&reg_3v3>;
+
+		port {
+			lcd_panel_in: endpoint {
+				remote-endpoint = <&lcd_display_out>;
+			};
+		};
+	};
+
+Then one needs to extend the dispX node:
+
+	lcd_display: disp1 {
+
+		port@1 {
+			reg = <1>;
+
+			lcd_display_out: endpoint {
+				remote-endpoint = <&lcd_panel_in>;
+			};
+		};
+	};