media: dt: bindings: tegra-vde: Document OPP and power domain

Document new OPP table and power domain properties of the video decoder
hardware.

Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>