dt-bindings: clock: cirrus,lochnagar: add top-level constraints

Properties with variable number of items per each device are expected to
have widest constraints in top-level "properties:" block and further
customized (narrowed) in "if:then:". Add missing top-level constraints
for clocks. Drop also redundant assigned-clocks properties, because
core dtschema allows them if clocks are provided.

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Acked-by: Conor Dooley <[e-mail]>
Signed-off-by: Stephen Boyd <[e-mail]>

Documentation/devicetree/bindings/clock/cirrus,lochnagar.yaml

···
     minItems: 1
     maxItems: 19
 
-  clocks: true
-  assigned-clocks: true
-  assigned-clock-parents: true
+  clocks:
+    minItems: 1
+    maxItems: 19
 
 additionalProperties: false