ASoC: dt-bindings: sun4i-spdif: Fix dma-names warning

Even though the H6 compatible has been properly added, the exeption for the
number of DMA channels hasn't been updated, leading in a validation
warning.

Fix this.

Fixes: b2045303 ("dt-bindings: sound: sun4i-spdif: Add Allwinner H6 compatible")
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://lore.kernel.org/r/20190828125209.28173-1-mripard@kernel.orgReviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/allwinner,sun4i-a10-spdif.yaml

@@ -70,7 +70,9 @@ allOf:
       properties:
         compatible:
           contains:
-            const: allwinner,sun8i-h3-spdif
+            enum:
+              - allwinner,sun8i-h3-spdif
+              - allwinner,sun50i-h6-spdif
 
     then:
       properties: