ASoC: dt-bindings: rockchip: Document pinctrl-names for i2s

This patch documents pinctrl-names for i2s.
Signed-off-by: Judy Hsiao <judyhsiao@chromium.org>
Link: https://lore.kernel.org/r/20220619095324.492678-4-judyhsiao@chromium.orgSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/rockchip-i2s.yaml

@@ -61,6 +61,13 @@ properties:
           - const: tx
           - const: rx
 
+  pinctrl-names:
+    oneOf:
+      - const: default
+      - items:
+          - const: bclk_on
+          - const: bclk_off
+
   power-domains:
     maxItems: 1