[media] doc-rst: Fix conversion for v4l2 core functions

The conversion from DocBook lead into some conversion issues,
basically due to the lack of proper support at kernel-doc.

So, address them:

- Now, the C files with the exported symbols also need to be
  added. So, all headers need to be included twice: one to
  get the structs/enums/.. and another one for the functions;

- Notes should use the ReST tag, as kernel-doc doesn't
  recognizes it anymore;

- Identation needs to be fixed, as ReST uses it to identify
  when a format "tag" ends.

- kernel-doc doesn't escape things like *pointer, so we
  need to manually add a escape char before it.

- On some cases, kernel-doc conversion requires violating
  the 80-cols, as otherwise it won't properly parse the
  source code.

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