ASoC: add bindings for ZTE zx-aud96p22 audio codec

It adds dt-bindings document for ZTE zx-aud96p22 audio codec.
Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/zte,zx-aud96p22.txt

+ZTE ZX AUD96P22 Audio Codec
+
+Required properties:
+ - compatible: Must be "zte,zx-aud96p22"
+ - #sound-dai-cells: Should be 0
+ - reg: I2C bus slave address of AUD96P22
+
+Example:
+
+	i2c0: i2c@1486000 {
+		compatible = "zte,zx296718-i2c";
+		reg = <0x01486000 0x1000>;
+		interrupts = <GIC_SPI 35 IRQ_TYPE_LEVEL_HIGH>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		clocks = <&audiocrm AUDIO_I2C0_WCLK>;
+		clock-frequency = <1600000>;
+
+		aud96p22: codec@22 {
+			compatible = "zte,zx-aud96p22";
+			#sound-dai-cells = <0>;
+			reg = <0x22>;
+		};
+	};