ASoC: Add documentation for KeemBay i2s

Document Intel KeemBay i2s DT bindings.
Signed-off-by: Sia Jee Heng <jee.heng.sia@intel.com>
Link: https://lore.kernel.org/r/1591682783-1923-4-git-send-email-jee.heng.sia@intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/intel,keembay-i2s.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+# Copyright 2020 Intel Corporation
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/sound/intel,keembay-i2s.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Intel KeemBay I2S Device Tree Bindings
+
+maintainers:
+  - Sia, Jee Heng <jee.heng.sia@intel.com>
+
+description: |
+ Intel KeemBay I2S
+
+properties:
+  compatible:
+    enum:
+      - intel,keembay-i2s
+
+  "#sound-dai-cells":
+    const: 0
+
+  reg:
+    items:
+      - description: I2S configuration
+
+  reg-names:
+    items:
+      - const: i2s-regs
+      - const: i2s_gen_cfg
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: Bus Clock
+      - description: Module Clock
+
+  clock-names:
+    items:
+      - const: osc
+      - const: apb_clk
+
+required:
+  - compatible
+  - "#sound-dai-cells"
+  - reg
+  - clocks
+  - clock-names
+  - interrupts
+
+examples:
+  - |
+     #include <dt-bindings/interrupt-controller/arm-gic.h>
+     #include <dt-bindings/interrupt-controller/irq.h>
+     #define KEEM_BAY_PSS_AUX_I2S3
+     #define KEEM_BAY_PSS_I2S3
+     i2s3: i2s@20140000 {
+         compatible = "intel,keembay-i2s";
+         #sound-dai-cells = <0>;
+         reg = <0x20140000 0x200 0x202a00a4 0x4>;
+         reg-names = "i2s-regs", "i2s_gen_cfg";
+         interrupts = <GIC_SPI 120 IRQ_TYPE_LEVEL_HIGH>;
+         clock-names = "osc", "apb_clk";
+         clocks = <&scmi_clk KEEM_BAY_PSS_AUX_I2S3>, <&scmi_clk KEEM_BAY_PSS_I2S3>;
+     };