V4L/DVB: sn9c102 / zc0301: Handle webcams when no gspca subdriver conflict

Some webcams handled by both sn9c102 or zc0301 and some gspca subdrivers
(sonixb, sonixj and zc3xx) were not handled when gspca was generated but
not the associated subdrivers.

Signed-off-by: Jean-François Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>