dt-bindings: mfd: syscon: Require specific compatible also for simple-mfd

The syscon bindings require a device specific compatible, beside the
"syscon".  However schema counts "simple-mfd" as such, which allows
simple-mfd+syscon to sneak in.

Adjust the match to be sure simple-mfd also comes with a device specific
compatible.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20220817142246.828762-5-krzysztof.kozlowski@linaro.org

Documentation/devicetree/bindings/mfd/syscon.yaml

@@ -72,7 +72,7 @@ properties:
       - contains:
           const: syscon
         minItems: 2
-        maxItems: 4  # Should be enough
+        maxItems: 5  # Should be enough
 
   reg:
     maxItems: 1
@@ -93,6 +93,18 @@ required:
   - compatible
   - reg
 
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: simple-mfd
+    then:
+      properties:
+        compatible:
+          minItems: 3
+          maxItems: 5
+
 additionalProperties: true
 
 examples: