dt-bindings: rtc: sun6i: Add H616 compatible string

Add the obvious compatible name to the existing RTC binding.
The actual RTC part of the device uses a different day/month/year
storage scheme, so it's not compatible with the previous devices.
Also the clock part is quite different, as there is no external 32K LOSC
oscillator input.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>

Documentation/devicetree/bindings/rtc/allwinner,sun6i-a31-rtc.yaml

@@ -26,6 +26,7 @@ properties:
           - const: allwinner,sun50i-a64-rtc
           - const: allwinner,sun8i-h3-rtc
       - const: allwinner,sun50i-h6-rtc
+      - const: allwinner,sun50i-h616-rtc
 
   reg:
     maxItems: 1
@@ -105,6 +106,20 @@ allOf:
           minItems: 3
           maxItems: 3
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: allwinner,sun50i-h616-rtc
+
+    then:
+      properties:
+        clock-output-names:
+          minItems: 3
+          maxItems: 3
+        clocks:
+          maxItems: 0
+
   - if:
       properties:
         compatible: