[media] gspca - sonixj: Bad sensor mode at start time

The 'open-drain' mode was not reset when starting the webcams.
This problem was introduced by commit 0e4d413a

 and
its exact effects are unknown.

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