[media] v4l2-dv-timings: add new helper module

This module makes it easy to filter valid timings from the full list of
CEA and DMT timings based on the timings capabilities.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>