V4L/DVB: gspca - sonixj: Add sensor soi768

The webcams 0c45:613e may contain the sensors ov7630 or soi768.
A sensor probe is done at init time when the sensor is declared ov7630.

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