media: dvb uAPI docs: adjust return value ioctl descriptions

There are several issues on the return value for ioctls:

- Text is confusing;
- Some error codes don't exist;
- The non-generic error codes should come before the text
  that points to the generic error codes;
- Tables don't contain column size hints;
- Some references are not marked as such.

Correct them.

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