DVBS2API introduced two new ioctls that allows changing/getting details about newer
video standards like DVB-S2 and ISDB-T. There are lots of thing to do in this chapter,
but, for now, just add a session there, in order to allow make to not complain about
undefined symbol.

With this patch, all ioctls at the frontend.h API were somehow documented.

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

We'll need to add the documentation for FE_[GET|SET]_PROPERTY that
is not specific to isdb-t. Instead of doing it at frontend.xml,
it is better to have a separate session for it. Also, isdbt.xml assumes
that those ioctls were already introduced, and documents several exisiting
properties. So, better to just rename it and add the documentation for it,
together with each existing property there.

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