drm/i915: Pass atomic state to verify_connector_state

This gets rid of a warning that the connectors are used without locking
when doing a nonblocking modeset.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1478609742-13603-11-git-send-email-maarten.lankhorst@linux.intel.com