V4L/DVB (8550): gspca: Change a bit the init of ov7660 and Sonix JPEG bridges.

Set back some values of gspcav1 in init of sonixj sensor ov7660.
Add some comments.

Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>