ARM: tegra: Add common device-tree for LVDS display panels of Tegra30 ASUS tablets

All Tegra30 ASUS tablets have a similar design pattern in terms of
hardware integration of LVDS display panels, like exactly the same GPIOs
are used for power and reset, etc. Add a common device-tree for LVDS
display panels of Tegra30 ASUS tablets to avoid replicating the
boilerplate panel description.

[digetx@gmail.com: factored out common part into separate patch and wrote commit message]
Co-developed-by: Svyatoslav Ryhel <clamor95@gmail.com>
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Signed-off-by: Maxim Schwalm <maxim.schwalm@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm/boot/dts/tegra30-asus-lvds-display.dtsi

+// SPDX-License-Identifier: GPL-2.0
+
+/* This dtsi file describes parts common for Asus T30 devices with a LVDS panel. */
+
+/ {
+	host1x@50000000 {
+		lcd: dc@54200000 {
+			rgb {
+				status = "okay";
+
+				port@0 {
+					dpi_output: endpoint {
+						remote-endpoint = <&bridge_input>;
+						bus-width = <24>;
+					};
+				};
+			};
+		};
+	};
+
+	display-panel {
+		power-supply = <&vdd_pnl>;
+		ddc-i2c-bus = <&lcd_ddc>;
+		backlight = <&backlight>;
+
+		port {
+			panel_input: endpoint {
+				remote-endpoint = <&bridge_output>;
+			};
+		};
+	};
+
+	/* Texas Instruments SN75LVDS83B LVDS Transmitter */
+	lvds-encoder {
+		compatible = "ti,sn75lvds83", "lvds-encoder";
+
+		powerdown-gpios = <&gpio TEGRA_GPIO(N, 6) GPIO_ACTIVE_LOW>;
+		power-supply = <&vdd_3v3_sys>;
+
+		ports {
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			port@0 {
+				reg = <0>;
+
+				bridge_input: endpoint {
+					remote-endpoint = <&dpi_output>;
+				};
+			};
+
+			port@1 {
+				reg = <1>;
+
+				bridge_output: endpoint {
+					remote-endpoint = <&panel_input>;
+				};
+			};
+		};
+	};
+};