drm/tegra: Boot VIC during runtime PM resume

With the new UAPI implementation, engines are powered on and off
when there are active jobs, and the core code handles channel
allocation. To accommodate that, boot the engine as part of
runtime PM instead of using the open_channel callback, which is
not used by the new submit path.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>