V4L/DVB (12283): gspca - sn9c20x: New subdriver for sn9c201 and sn9c202 bridges.

Signed-off-by: Brian Johnson <brijohn@gmail.com>
Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>