v4l2-dev: forgot to add VIDIOC_DV_TIMINGS_CAP.

The VIDIOC_DV_TIMINGS_CAP ioctl check wasn't added to determine_valid_ioctls().
This caused this ioctl to always return -ENOTTY.

The cause for this was that for 3.5 two patch series were merged, one
changing V4L2 core ioctl handling and one adding new functionality, and
some of the new functionality wasn't handled by the new V4L2 core code.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
[ Taking it directly due to vacations  - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>