dt-bindings: sound: cs42l51: Remove unneeded I2C unit name

The following warning is seen with 'make dt_binding_check':

Documentation/devicetree/bindings/sound/cirrus,cs42l51.example.dts:18.15-34.11: Warning (unit_address_vs_reg): /example-0/i2c@0: node has a unit name, but no reg or ranges property

Fix it by removing the unneeded i2c unit name.
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200327155721.7596-1-festevam@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/cirrus,cs42l51.yaml

@@ -49,7 +49,7 @@ required:
 examples:
   - |
     #include <dt-bindings/gpio/gpio.h>
-    i2c@0 {
+    i2c {
       #address-cells = <1>;
       #size-cells = <0>;