dt-bindings: display: bridge: Add YAML schema for Synopsys DW-HDMI

Add a .yaml schema containing the common properties for the Synopsys
DesignWare HDMI TX controller. This isn't a full device tree binding
specification, but is meant to be referenced by platform-specific
bindings for the IP core.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/display/bridge/synopsys,dw-hdmi.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/bridge/synopsys,dw-hdmi.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Common Properties for Synopsys DesignWare HDMI TX Controller
+
+maintainers:
+  - Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
+
+description: |
+  This document defines device tree properties for the Synopsys DesignWare HDMI
+  TX controller (DWC HDMI TX) IP core. It doesn't constitute a full device tree
+  binding specification by itself but is meant to be referenced by device tree
+  bindings for the platform-specific integrations of the DWC HDMI TX.
+
+  When referenced from platform device tree bindings the properties defined in
+  this document are defined as follows. The platform device tree bindings are
+  responsible for defining whether each property is required or optional.
+
+properties:
+  reg:
+    maxItems: 1
+
+  reg-io-width:
+    description:
+      Width (in bytes) of the registers specified by the reg property.
+    allOf:
+      - $ref: /schemas/types.yaml#/definitions/uint32
+      - enum: [1, 4]
+    default: 1
+
+  clocks:
+    minItems: 2
+    maxItems: 5
+    items:
+      - description: The bus clock for either AHB and APB
+      - description: The internal register configuration clock
+    additionalItems: true
+
+  clock-names:
+    minItems: 2
+    maxItems: 5
+    items:
+      - const: iahb
+      - const: isfr
+    additionalItems: true
+
+  interrupts:
+    maxItems: 1
+
+additionalProperties: true
+
+...