media: dvb_frontend.h: improve kernel-doc markups

Several minor adjustments at the kernel-doc markups:

- some syntax fixes;
- some cross-references;
- add cross-references for the mentioned ioctls;
- some constants marked as such.

No functional changes.

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