V4L/DVB (10266): Add support for TurboSight TBS6920 DVB-S2 PCI-e card.

TurboSight TBS6920 DVB-S2 PCI-e card contains cx23885 PCI-e bridge
and cx24116 demodulator.
http://www.linuxtv.org/wiki/index.php/TBS_6920


The card tested by me (Igor).

Signed-off-by: Igor M. Liplianin <liplianin@me.by>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>