dt-bindings: display: bridge: fork out ti, ds90c185 from lvds-transmitter

DS90C185 has a shutdown pin which does not fit in the lvds-transmitter
binding, which is meant to be generic.

The sister chip DS90C187 is similar to DS90C185, describe it here as well.
Signed-off-by: Peter Rosin <peda@axentia.se>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190111151843.11114-2-peda@axentia.se

Documentation/devicetree/bindings/display/bridge/lvds-transmitter.txt

@@ -22,13 +22,11 @@ among others.
 
 Required properties:
 
-- compatible: Must be one or more of the following
-  - "ti,ds90c185" for the TI DS90C185 FPD-Link Serializer
-  - "lvds-encoder" for a generic LVDS encoder device
+- compatible: Must be "lvds-encoder"
 
-  When compatible with the generic version, nodes must list the
-  device-specific version corresponding to the device first
-  followed by the generic version.
+  Any encoder compatible with this generic binding, but with additional
+  properties not listed here, must list a device specific compatible first
+  followed by this generic compatible.
 
 Required nodes:
 

Documentation/devicetree/bindings/display/bridge/ti,ds90c185.txt

+Texas Instruments FPD-Link (LVDS) Serializer
+--------------------------------------------
+
+The DS90C185 and DS90C187 are low-power serializers for portable
+battery-powered applications that reduces the size of the RGB
+interface between the host GPU and the display.
+
+Required properties:
+
+- compatible: Should be
+  "ti,ds90c185", "lvds-encoder"  for the TI DS90C185 FPD-Link Serializer
+  "ti,ds90c187", "lvds-encoder"  for the TI DS90C187 FPD-Link Serializer
+
+Optional properties:
+
+- powerdown-gpios: Power down control GPIO (the PDB pin, active-low)
+
+Required nodes:
+
+The devices have two video ports. Their connections are modeled using the OF
+graph bindings specified in Documentation/devicetree/bindings/graph.txt.
+
+- Video port 0 for parallel input
+- Video port 1 for LVDS output
+
+
+Example
+-------
+
+lvds-encoder {
+	compatible = "ti,ds90c185", "lvds-encoder";
+
+	powerdown-gpios = <&gpio 17 GPIO_ACTIVE_LOW>;
+
+	ports {
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		port@0 {
+			reg = <0>;
+
+			lvds_enc_in: endpoint {
+				remote-endpoint = <&lcdc_out_rgb>;
+			};
+		};
+
+		port@1 {
+			reg = <1>;
+
+			lvds_enc_out: endpoint {
+				remote-endpoint = <&lvds_panel_in>;
+			};
+		};
+	};
+};