dt: bindings: tegra20-emc: Document clock property

Embedded memory controller has a corresponding clock, document the clock
property.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
1 file changed