dt-bindings: memory-controllers: renesas,rpc-if: 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.

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

Documentation/devicetree/bindings/memory-controllers/renesas,rpc-if.yaml

···
       - const: dirmap
       - const: wbuf
 
-  clocks: true
+  clocks:
+    minItems: 1
+    maxItems: 2
 
   interrupts:
     maxItems: 1