dt-bindings: rtc: sun6i: Add the R40 RTC compatible

The R40 has a pretty different RTC compared to the other SoCs we've
encountered so far, the most important difference being that it now has
only a single interrupt, compared to the previous SoCs having two.

Let's add a compatible for that.
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

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

@@ -19,9 +19,7 @@ properties:
       - const: allwinner,sun6i-a31-rtc
       - const: allwinner,sun8i-a23-rtc
       - const: allwinner,sun8i-h3-rtc
-      - items:
-          - const: allwinner,sun8i-r40-rtc
-          - const: allwinner,sun8i-h3-rtc
+      - const: allwinner,sun8i-r40-rtc
       - const: allwinner,sun8i-v3-rtc
       - const: allwinner,sun50i-h5-rtc
       - items:
@@ -32,6 +30,8 @@ properties:
     maxItems: 1
 
   interrupts:
+    minItems: 1
+    maxItems: 2
     items:
       - description: RTC Alarm 0
       - description: RTC Alarm 1
@@ -69,6 +69,7 @@ allOf:
           contains:
             enum:
               - allwinner,sun8i-a23-rtc
+              - allwinner,sun8i-r40-rtc
               - allwinner,sun8i-v3-rtc
 
     then:
@@ -91,6 +92,24 @@ allOf:
           minItems: 3
           maxItems: 3
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: allwinner,sun8i-r40-rtc
+
+    then:
+      properties:
+        interrupts:
+          minItems: 1
+          maxItems: 1
+
+    else:
+      properties:
+        interrupts:
+          minItems: 2
+          maxItems: 2
+
 required:
   - "#clock-cells"
   - compatible