drm/i915: restore render clock gating on resume

Rather than restoring just a few clock gating registers on resume,
just reinitialize the whole thing.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
[anholt: Fixed up for RC6 support landed since the patch was written]
Signed-off-by: Eric Anholt <eric@anholt.net>
4 files changed