V4L/DVB: tm6000: bugfix video image

bugfix: Avoid loosing frames, causing image delays on some of the image lines.

[mchehab@redhat.com: Fix compilation breakage by merging with the patch fix]
Signed-off-by: Stefan Ringel <stefan.ringel@arcor.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>