dt-bindings: bus: qcom,ssc-block-bus: rework arrays and drop redundant minItems

There is no need to specify "minItems" if it equals to "maxItems".  On the
other hand number of items in an array can be specified via describing
items, which might bring some additional information.  This simplifies a
bit the binding.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220712154602.26994-1-krzysztof.kozlowski@linaro.org