A missed conversion prevents correct pixel format negotiation with client
drivers.
Reported-by: NAntonio Ospite <ospite@studenti.unina.it>
Signed-off-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>