dt-bindings: clock: mediatek: convert hifsys to the json-schema clock

This helps validating DTS files. Introduced changes:
1. Documented "reg" property
2. Documented "#reset-cells" property
3. Dropped "syscon" as it was incorrectly used
4. Adjusted "compatible" and "reg" in example

Signed-off-by: Rafał Miłecki <[email protected]>
Reviewed-by: Krzysztof Kozlowski <[email protected]>
Reviewed-by: AngeloGioacchino Del Regno <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Stephen Boyd <[email protected]>

Author: Rafał Miłecki

Documentation/devicetree/bindings/arm/mediatek/mediatek,hifsys.txt

@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/clock/mediatek,mt2701-hifsys.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: MediaTek HIFSYS clock and reset controller
+
+description:
+  The MediaTek HIFSYS controller provides various clocks and reset outputs to
+  the system.
+
+maintainers:
+  - Matthias Brugger <[email protected]>
+
+properties:
+  compatible:
+    oneOf:
+      - enum:
+          - mediatek,mt2701-hifsys
+          - mediatek,mt7622-hifsys
+      - items:
+          - enum:
+              - mediatek,mt7623-hifsys
+          - const: mediatek,mt2701-hifsys
+
+  reg:
+    maxItems: 1
+
+  "#clock-cells":
+    const: 1
+    description: The available clocks are defined in dt-bindings/clock/mt*-clk.h
+
+  "#reset-cells":
+    const: 1
+
+required:
+  - reg
+  - "#clock-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    clock-controller@1a000000 {
+        compatible = "mediatek,mt2701-hifsys";
+        reg = <0x1a000000 0x1000>;
+        #clock-cells = <1>;
+        #reset-cells = <1>;
+    };