dt-bindings: tegra-ccplex-cluster: Remove status from required properties

The "status" property is implied to be "okay" if it isn't present, so do
not mark it as required.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>