drm/i915: Prepare connectors for nonblocking checks.

intel_unpin_work may not take the list lock because it requires the connector_mutex.
To prevent taking locks we add an array of old and new state. The old state to free,
the new state to commit and verify.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1463490484-19540-18-git-send-email-maarten.lankhorst@linux.intel.com
Reviewed-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>