[media] zoran: fix compiler warning

drivers/media/video/zoran/zoran_driver.c: In function 'zoran_dqbuf':
drivers/media/video/zoran/zoran_driver.c:2197:21: warning: 'bs.frame' may be used uninitialized in this function

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>