dt-bindings: input: sun4i-lradc-keys: Add H616 compatible

The Allwinner H616 SoC has an LRADC which is compatible with the
versions in existing SoCs.
Add a compatible string for H616, with the R329 fallback. This is the
same as the D1, so put them into an enum.

Signed-off-by: James McGregor <[e-mail]>
Reviewed-by: Andre Przywara <[e-mail]>
Acked-by: Rob Herring (Arm) <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Chen-Yu Tsai <[e-mail]>

Documentation/devicetree/bindings/input/allwinner,sun4i-a10-lradc-keys.yaml

···
           - const: allwinner,sun8i-a83t-r-lradc
       - const: allwinner,sun50i-r329-lradc
       - items:
-          - const: allwinner,sun20i-d1-lradc
+          - enum:
+              - allwinner,sun50i-h616-lradc
+              - allwinner,sun20i-d1-lradc
           - const: allwinner,sun50i-r329-lradc
 
   reg: