drm/tegra: gr2d: Track interface version

Set the interface version implemented by the gr2d module. This allows
userspace to pass the correct command stream when programming the gr2d
module.

Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>