commit c4f9c4c2 upstream.

It's needed for 3 pipe support as well as just regular functionality
(e.g. DisplayPort).
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: Adam Jackson <ajax@redhat.com>
Tested-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Robert Hooker <robert.hooker@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>