[media] cx231xx: fix bulk transfer mode

The current cx231xx driver doesn't work with bulk transfer mode.
This patch makes it possible to use bulk transfer mode.

Signed-off-by: Terry Heo <terryheo@google.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>