drm/i915: enable output polling during S4 thaw

drm/i915: enable output polling during S4 thaw

To avoid processing hotplug events we disable connector polling for the
duration of S3 suspend. We also disable it for S4 freeze, and keep it
disabled after S4 thaw. This won't prevent though hotplug processing,
since we re-enable interrupts anyway. There is also no need to prevent
it at that time, since we reinitialize everything during thaw, so the
device is in a consistent state. So to simplify things enable polling
during thaw, which will allow us to handle S4 thaw the same way as S3
resume in an upcoming patch.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>