dt-bindings: clock: versal-clk: Fix Versal NET clock validation

The Versal NET clock controller compatible is specified as:
  compatible = "xlnx,versal-net-clk", "xlnx,versal-clk";

with xlnx,versal-clk listed as fallback. The original binding had
two separate if/then blocks - one matching xlnx,versal-clk (2 clocks)
and another matching xlnx,versal-net-clk (3 clocks). Since both
compatible strings are present, both conditions matched simultaneously
and JSON Schema applied the more restrictive 2-clock constraint,
causing false "too long" validation errors for Versal NET.

Define clock-names at the top-level and use if/then only to constrain
the clock count (2 for Versal, 3 for Versal NET). Add a dedicated
example for the Versal NET 3-clock configuration.

Fixes: 39118392d1 ("dt-bindings: Remove alt_ref from versal")
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://patch.msgid.link/202e448e57cf979e1b5be61da0bad7778defdd4e.1783516336.git.michal.simek@amd.com
Signed-off-by: Michal Simek <michal.simek@amd.com>

Documentation/devicetree/bindings/clock/xlnx,versal-clk.yaml

@@ -30,11 +30,17 @@ properties:
     description: List of clock specifiers which are external input
       clocks to the given clock controller.
     minItems: 2
-    maxItems: 3
+    items:
+      - description: reference clock
+      - description: alternate reference clock for programmable logic
+      - description: alternate reference clock
 
   clock-names:
     minItems: 2
-    maxItems: 3
+    items:
+      - const: ref
+      - const: pl_alt_ref
+      - const: alt_ref
 
 required:
   - compatible
@@ -45,45 +51,24 @@ required:
 additionalProperties: false
 
 allOf:
-  - if:
-      properties:
-        compatible:
-          contains:
-            enum:
-              - xlnx,versal-clk
-
-    then:
-      properties:
-        clocks:
-          items:
-            - description: reference clock
-            - description: alternate reference clock for programmable logic
-
-        clock-names:
-          items:
-            - const: ref
-            - const: pl_alt_ref
-
   - if:
       properties:
         compatible:
           contains:
             enum:
               - xlnx,versal-net-clk
-
     then:
       properties:
         clocks:
-          items:
-            - description: reference clock
-            - description: alternate reference clock for programmable logic
-            - description: alternate reference clock
-
+          minItems: 3
         clock-names:
-          items:
-            - const: ref
-            - const: pl_alt_ref
-            - const: alt_ref
+          minItems: 3
+    else:
+      properties:
+        clocks:
+          maxItems: 2
+        clock-names:
+          maxItems: 2
 
 examples:
   - |
@@ -99,4 +84,12 @@ examples:
         };
       };
     };
+
+  - |
+    clock-controller {
+      compatible = "xlnx,versal-net-clk", "xlnx,versal-clk";
+      clocks = <&ref>, <&pl_alt_ref>, <&alt_ref>;
+      clock-names = "ref", "pl_alt_ref", "alt_ref";
+      #clock-cells = <1>;
+    };
 ...