drm/tegra: gr3d: Support generic power domain and runtime PM

Add runtime power management and support generic power domains.

Reviewed-by: Ulf Hansson <[email protected]>
Tested-by: Peter Geis <[email protected]> # Ouya T30
Tested-by: Paul Fertser <[email protected]> # PAZ00 T20
Tested-by: Nicolas Chauvet <[email protected]> # PAZ00 T20 and TK1 T124
Tested-by: Matt Merhar <[email protected]> # Ouya T30
Signed-off-by: Dmitry Osipenko <[email protected]>
Signed-off-by: Thierry Reding <[email protected]>

Author: digetx