dt-bindings: display: ingenic,jz4780-hdmi: Add missing clock-names

The binding references synopsys,dw-hdmi.yaml schema which defines both
'clocks' and 'clock-names' with variable length, therefore we need here
also same constraint for 'clock-names' as for 'clocks'.

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Rob Herring (Arm) <[e-mail]>

Documentation/devicetree/bindings/display/bridge/ingenic,jz4780-hdmi.yaml

···
   clocks:
     maxItems: 2
 
+  clock-names:
+    maxItems: 2
+
   ports:
     $ref: /schemas/graph.yaml#/properties/ports