dt-bindings: memory-controllers: renesas,rpc-if: add top-level constraints

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 <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240818172930.121898-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>