dt-bindings: one file of all simple DSI panels

To complement panel-simple.yaml, create panel-simple-dsi.yaml.
panel-simple-dsi-yaml are for all simple DSP panels with a single
power-supply and optional backlight / enable GPIO.

Migrate panasonic,vvx10f034n00 over to the new file.

The objectives with one file for all the simple DSI panels are:
    - Make it simpler to add bindings for simple DSI panels
    - Keep the number of bindings file lower
    - Keep the binding documentation for simple DSI panels more consistent
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Philippe Cornu <philippe.cornu@st.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Yannick Fertre <yannick.fertre@st.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Cc: devicetree@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20200206133344.724-2-benjamin.gaignard@st.com

Documentation/devicetree/bindings/display/panel/panasonic,vvx10f034n00.txt

-Panasonic 10" WUXGA TFT LCD panel
-
-Required properties:
-- compatible: should be "panasonic,vvx10f034n00"
-- reg: DSI virtual channel of the peripheral
-- power-supply: phandle of the regulator that provides the supply voltage
-
-Optional properties:
-- backlight: phandle of the backlight device attached to the panel
-
-Example:
-
-	mdss_dsi@fd922800 {
-		panel@0 {
-			compatible = "panasonic,vvx10f034n00";
-			reg = <0>;
-			power-supply = <&vreg_vsp>;
-			backlight = <&lp8566_wled>;
-		};
-	};

Documentation/devicetree/bindings/display/panel/panel-simple-dsi.yaml

+# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/panel/panel-simple-dsi.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Simple DSI panels with a single power-supply
+
+maintainers:
+  - Thierry Reding <thierry.reding@gmail.com>
+  - Sam Ravnborg <sam@ravnborg.org>
+
+description: |
+  This binding file is a collection of the DSI panels that
+  requires only a single power-supply.
+  There are optionally a backlight and an enable GPIO.
+  The panel may use an OF graph binding for the association to the display,
+  or it may be a direct child node of the display.
+
+  If the panel is more advanced a dedicated binding file is required.
+
+allOf:
+  - $ref: panel-common.yaml#
+
+properties:
+
+  compatible:
+    enum:
+      # compatible must be listed in alphabetical order, ordered by compatible.
+      # The description in the comment is mandatory for each compatible.
+
+        # Panasonic 10" WUXGA TFT LCD panel
+      - panasonic,vvx10f034n00
+
+  reg:
+    maxItems: 1
+    description: DSI virtual channel
+
+  backlight: true
+  enable-gpios: true
+  port: true
+  power-supply: true
+
+additionalProperties: false
+
+required:
+  - compatible
+  - power-supply
+  - reg
+
+examples:
+  - |
+    mdss_dsi@fd922800 {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      panel@0 {
+        compatible = "panasonic,vvx10f034n00";
+        reg = <0>;
+        power-supply = <&vcc_lcd_reg>;
+
+        port {
+          panel: endpoint {
+            remote-endpoint = <&ltdc_out>;
+          };
+        };
+      };
+    };