[media] cx231xx: Add support for Iconbit U100

This patch adds support for the "Iconbit Analog Stick U100 FM".
Only composite & s-video inputs, no tuner support now.

Signed-off-by: Igor Novgorodov <igor@novg.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>