drm/i915: Convert intel DVO connector to atomic

No properties are supported, so just use the helper and reject everything.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1491815239-10685-6-git-send-email-maarten.lankhorst@linux.intel.com


Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>