dt-bindings: ASoC: Add tas2770 smart PA dt bindings

Add tas2770 smart PA dt bindings
Signed-off-by: Frank Shi <shifu0704@thundersoft.com>
Link: https://lore.kernel.org/r/1568962709-19185-1-git-send-email-shifu0704@thundersoft.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/tas2770.txt

+Texas Instruments TAS2770 Smart PA
+
+The TAS2770 is a mono, digital input Class-D audio amplifier optimized for
+efficiently driving high peak power into small loudspeakers.
+Integrated speaker voltage and current sense provides for
+real time monitoring of loudspeaker behavior.
+
+Required properties:
+
+ - compatible:	   - Should contain "ti,tas2770".
+ - reg:		       - The i2c address. Should contain <0x4c>, <0x4d>,<0x4e>, or <0x4f>.
+ - #address-cells  - Should be <1>.
+ - #size-cells     - Should be <0>.
+ - ti,asi-format:  - Sets TDM RX capture edge. 0->Rising; 1->Falling.
+ - ti,imon-slot-no:- TDM TX current sense time slot.
+ - ti,vmon-slot-no:- TDM TX voltage sense time slot.
+
+Optional properties:
+
+- interrupt-parent: the phandle to the interrupt controller which provides
+                     the interrupt.
+- interrupts: interrupt specification for data-ready.
+
+Examples:
+
+    tas2770@4c {
+                compatible = "ti,tas2770";
+                reg = <0x4c>;
+                #address-cells = <1>;
+                #size-cells = <0>;
+                interrupt-parent = <&msm_gpio>;
+                interrupts = <97 0>;
+                ti,asi-format = <0>;
+                ti,imon-slot-no = <0>;
+                ti,vmon-slot-no = <2>;
+        };
+