[media] fix broken references on dvb/video*rst

Trivially fix those broken references, by copying the structs
fron the header, just like other API documentation at the
DVB side.

This doesn't have the level of quality used at the V4L2 side
of the API, but, as this documents a deprecated API, used
only by av7110 driver, it doesn't make much sense to invest
time making it better.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>