ASoC: Added device tree binding for max98373 amplifier

Signed-off-by: Ryan Lee <ryans.lee@maximintegrated.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/max98373.txt

@@ -0,0 +1,40 @@
+Maxim Integrated MAX98373 Speaker Amplifier
+
+This device supports I2C.
+
+Required properties:
+
+ - compatible : "maxim,max98373"
+
+ - reg : the I2C address of the device.
+
+Optional properties:
+
+  - maxim,vmon-slot-no : slot number used to send voltage information
+                   or in inteleave mode this will be used as
+                   interleave slot.
+                   slot range : 0 ~ 15,  Default : 0
+
+  - maxim,imon-slot-no : slot number used to send current information
+                   slot range : 0 ~ 15,  Default : 0
+
+  - maxim,spkfb-slot-no : slot number used to send speaker feedback information
+                   slot range : 0 ~ 15,  Default : 0
+
+  - maxim,interleave-mode : For cases where a single combined channel
+		   for the I/V sense data is not sufficient, the device can also be configured
+		   to share a single data output channel on alternating frames.
+		   In this configuration, the current and voltage data will be frame interleaved
+		   on a single output channel.
+                   Boolean, define to enable the interleave mode, Default : false
+
+Example:
+
+codec: max98373@31 {
+   compatible = "maxim,max98373";
+   reg = <0x31>;
+   maxim,vmon-slot-no = <0>;
+   maxim,imon-slot-no = <1>;
+   maxim,spkfb-slot-no = <2>;
+   maxim,interleave-mode;
+};