[media] doc-rst: fix media kAPI documentation

I ended by adding twice each media header, because I saw some
missing stuff at the documents. It seems it was my mistake,
as everything seems to be there.

So, remove those extra stuff, to avoid duplicating the
documentation of the functions.

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