dt-bindings: clock: lan966x: Add LAN966X Clock Controller

This adds the DT bindings documentation for lan966x SoC
generic clock controller.
Signed-off-by: Kavyasree Kotagiri <kavyasree.kotagiri@microchip.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20211103061935.25677-3-kavyasree.kotagiri@microchip.com

Documentation/devicetree/bindings/clock/microchip,lan966x-gck.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/clock/microchip,lan966x-gck.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip LAN966X Generic Clock Controller
+
+maintainers:
+  - Kavyasree Kotagiri <kavyasree.kotagiri@microchip.com>
+
+description: |
+  The LAN966X Generic clock controller contains 3 PLLs - cpu_clk,
+  ddr_clk and sys_clk. This clock controller generates and supplies
+  clock to various peripherals within the SoC.
+
+properties:
+  compatible:
+    const: microchip,lan966x-gck
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: CPU clock source
+      - description: DDR clock source
+      - description: System clock source
+
+  clock-names:
+    items:
+      - const: cpu
+      - const: ddr
+      - const: sys
+
+  '#clock-cells':
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+  - '#clock-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    clks: clock-controller@e00c00a8 {
+        compatible = "microchip,lan966x-gck";
+        #clock-cells = <1>;
+        clocks = <&cpu_clk>, <&ddr_clk>, <&sys_clk>;
+        clock-names = "cpu", "ddr", "sys";
+        reg = <0xe00c00a8 0x38>;
+    };
+...