drm/tegra: dc: Disable plane if it is invisible

On Tegra20 if plane has width or height equal to 0, it will be infinitely
wide or tall. Let's disable the plane if it is invisible on atomic state
committing to fix the issue. The Rockchip DRM driver does the same.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Erik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>