ASoC: simple-card: Pass 'reg' property in the examples

Since unit addresses are passed to simple-audio-card,dai-link a
corresponding 'reg' property is needed, otherwise dtc complains
(when building with W=1) in case someone copies the bindings example
into a real dts file:

Warning (unit_address_vs_reg): Node /sound-digital/simple-audio-card,dai-link@0 has a unit name, but no reg property

Improve the example by passing the correct 'reg' properties.
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/simple-card.txt

@@ -140,6 +140,7 @@ sound {
 	simple-audio-card,name = "Cubox Audio";
 
 	simple-audio-card,dai-link@0 {		/* I2S - HDMI */
+		reg = <0>;
 		format = "i2s";
 		cpu {
 			sound-dai = <&audio1 0>;
@@ -150,6 +151,7 @@ sound {
 	};
 
 	simple-audio-card,dai-link@1 {		/* S/PDIF - HDMI */
+		reg = <1>;
 		cpu {
 			sound-dai = <&audio1 1>;
 		};
@@ -159,6 +161,7 @@ sound {
 	};
 
 	simple-audio-card,dai-link@2 {		/* S/PDIF - S/PDIF */
+		reg = <2>;
 		cpu {
 			sound-dai = <&audio1 1>;
 		};