ASoC: tas2552: Improve DT binding document example

Improve DT binding document example by providing the mandatory
regulator properties.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/Documentation/devicetree/bindings/sound/tas2552.txt b/Documentation/devicetree/bindings/sound/tas2552.txt
index c49992c..54c1c87 100644
--- a/Documentation/devicetree/bindings/sound/tas2552.txt
+++ b/Documentation/devicetree/bindings/sound/tas2552.txt
@@ -25,6 +25,9 @@
 tas2552: tas2552@41 {
 	compatible = "ti,tas2552";
 	reg = <0x41>;
+	vbat-supply = <&reg_vbat>;
+	iovdd-supply = <&reg_iovdd>;
+	avdd-supply = <&reg_avdd>;
 	enable-gpio = <&gpio4 2 GPIO_ACTIVE_HIGH>;
 };