dt-bindings: iio: adc: Add GPADC for Allwinner H616

Add support for the GPADC for the Allwinner H616. It is identical to
the existing ADC for the D1/T113s/R329/T507 SoCs.
Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20240417170423.20640-3-macroalpha82@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/adc/allwinner,sun20i-d1-gpadc.yaml

@@ -11,8 +11,13 @@ maintainers:
 
 properties:
   compatible:
-    enum:
-      - allwinner,sun20i-d1-gpadc
+    oneOf:
+      - enum:
+          - allwinner,sun20i-d1-gpadc
+      - items:
+          - enum:
+              - allwinner,sun50i-h616-gpadc
+          - const: allwinner,sun20i-d1-gpadc
 
   "#io-channel-cells":
     const: 1