ASoC: ak5386: Add regulators to documentation and fix sparse warning

Document the newly added regulators to the DT binding document.

Also, "static const char const *x" is not identical to "static const
char * const x", which sparse now complains about. Fix it.
Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

Documentation/devicetree/bindings/sound/ak5386.txt

@@ -10,10 +10,14 @@ Optional properties:
 
   - reset-gpio : a GPIO spec for the reset/power down pin.
 		 If specified, it will be deasserted at probe time.
+  - va-supply : a regulator spec, providing 5.0V
+  - vd-supply : a regulator spec, providing 3.3V
 
 Example:
 
 spdif: ak5386@0 {
 	compatible = "asahi-kasei,ak5386";
 	reset-gpio = <&gpio0 23>;
+	va-supply = <&vdd_5v0_reg>;
+	vd-supply = <&vdd_3v3_reg>;
 };

sound/soc/codecs/ak5386.c

@@ -19,7 +19,7 @@
 #include <sound/pcm.h>
 #include <sound/initval.h>
 
-static const char const *supply_names[] = {
+static const char * const supply_names[] = {
 	"va", "vd"
 };