V4L/DVB (8817): gspca: LED and proble changes in sonixb.

- turn the led of the cam off after plugging in the cam
- move the probe code from open to config, so that if the probe fails
  we never register

Signed-off-by: Hans de Goede <j.w.r.degoede@hhs.nl>
Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>