ASoC: qcom: document apq8016 sbc machine driver bindings

* Qualcomm Technologies APQ8016 SBC ASoC machine driver

This node models the Qualcomm Technologies APQ8016 SBC ASoC machine driver

Required properties:

- compatible		: "qcom,apq8016-sbc-sndcard"

- pinctrl-N		: One property must exist for each entry in

			  pinctrl-names.  See ../pinctrl/pinctrl-bindings.txt

			  for details of the property values.

- pinctrl-names		: Must contain a "default" entry.

- reg			: Must contain an address for each entry in reg-names.

- reg-names		: A list which must include the following entries:

				* "mic-iomux"

				* "spkr-iomux"

- qcom,model		: Name of the sound card.

Dai-link subnode properties and subnodes:

Required dai-link subnodes:

- cpu					: CPU   sub-node

- codec					: CODEC sub-node

Required CPU/CODEC subnodes properties:

-link-name		: Name of the dai link.

-sound-dai		: phandle and port of CPU/CODEC

-capture-dai		: phandle and port of CPU/CODEC

Example:

sound: sound {

	compatible = "qcom,apq8016-sbc-sndcard";

	reg = <0x07702000 0x4>, <0x07702004 0x4>;

	reg-names = "mic-iomux", "spkr-iomux";

	qcom,model = "DB410c";

	/* I2S - Internal codec */

	internal-dai-link@0 {

		cpu { /* PRIMARY */

			sound-dai = <&lpass MI2S_PRIMARY>;

		};

		codec {

			sound-dai = <&wcd_codec 0>;

		};

	};

	/* External Primary or External Secondary -ADV7533 HDMI */

	external-dai-link@0 {

		link-name = "ADV7533";

		cpu { /* QUAT */

			sound-dai = <&lpass MI2S_QUATERNARY>;

		};

		codec {

			sound-dai = <&adv_bridge 0>;

		};

	};

};