ASoC: cs42xx8: add reset-gpios in binding document

Add reset-gpios property, which is optional.
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/cs42xx8.txt

@@ -14,6 +14,11 @@ Required properties:
   - VA-supply, VD-supply, VLS-supply, VLC-supply: power supplies for the device,
     as covered in Documentation/devicetree/bindings/regulator/regulator.txt
 
+Optional properties:
+
+  - reset-gpios : a GPIO spec to define which pin is connected to the chip's
+    !RESET pin
+
 Example:
 
 cs42888: codec@48 {
@@ -25,4 +30,5 @@ cs42888: codec@48 {
 	VD-supply = <&reg_audio>;
 	VLS-supply = <&reg_audio>;
 	VLC-supply = <&reg_audio>;
+	reset-gpios = <&pca9557_b 1 GPIO_ACTIVE_LOW>;
 };