Revert "drm/i915: set conservative clock gating values on VLV v2"

We're disabling a boatload of clock gating features on VLV. Maybe these
days we don't need to do that. At least I'm not aware of any workarounds
with this level of paranoia.

This reverts commit 4e8c84a5.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>