Some system supports hybrid graphics and its discrete VGA
does not have any connectors and therefore has no _DOD method.

BugLink: http://bugs.launchpad.net/bugs/1634607Signed-off-by: Alex Hung <alex.hung@canonical.com>
Reviewed-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit e34fbbac)
Signed-off-by: Alex Hung <alex.hung@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>