drm/i915: Pass atomic state to crtc enable/disable functions

This is required for supporting nonblocking modesets. Iterating over
the connector list will no longer be allowed when we don't hold
connection_mutex, so we have to use the atomic state.

Fix disable_noatomic by populating the minimal state required to
disable a connector.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470755054-32699-3-git-send-email-maarten.lankhorst@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>