dt-bindings: example-schema: don't use enum as fallback, explain clock-names

Compatibles with multiple entries should have usually only one fallback
compatible thus enum followed by enum is not a common case.  Use 'const'
as second compatible to show the recommended approach.

Explain also when clock-names are not really necessary.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230612092611.12385-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/example-schema.yaml

@@ -52,8 +52,7 @@ properties:
               - vendor,soc4-ip
               - vendor,soc3-ip
               - vendor,soc2-ip
-          - enum:
-              - vendor,soc1-ip
+          - const: vendor,soc1-ip
         # additionalItems being false is implied
         # minItems/maxItems equal to 2 is implied
       - items:
@@ -85,6 +84,9 @@ properties:
       discouraged.
 
   clock-names:
+    # For single-entry lists in clocks, resets etc., the xxx-names often do not
+    # bring any value, especially if they copy the IP block name.  In such case
+    # just skip the xxx-names.
     items:
       - const: bus