dt-bindings: extcon: maxim,max77843: Add MAX77843 bindings

Document the bindings for MAX77843 MUIC/extcon driver, based on
Exynos5433 TM2 devicetree.  These are neither accurate nor finished
bindings but at least allow parsing existing DTS files.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20220111174805.223732-3-krzysztof.kozlowski@canonical.com

Documentation/devicetree/bindings/extcon/maxim,max77843.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/extcon/maxim,max77843.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Maxim MAX77843 MicroUSB and Companion Power Management IC Extcon
+
+maintainers:
+  - Chanwoo Choi <cw00.choi@samsung.com>
+  - Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
+
+description: |
+  This is a part of device tree bindings for Maxim MAX77843 MicroUSB
+  Integrated Circuit (MUIC).
+
+  See also Documentation/devicetree/bindings/mfd/maxim,max77843.yaml for
+  additional information and example.
+
+properties:
+  compatible:
+    const: maxim,max77843-muic
+
+  connector:
+    $ref: /schemas/connector/usb-connector.yaml#
+
+  ports:
+    $ref: /schemas/graph.yaml#/properties/port
+    description:
+      Any connector to the data bus of this controller should be modelled using
+      the OF graph bindings specified
+    properties:
+      port:
+        $ref: /schemas/graph.yaml#/properties/port
+
+required:
+  - compatible
+  - connector
+
+additionalProperties: false