V4L/DVB: gspca - sq930x: Change image format to Bayer mode

The JPEG format did not work fine. The Bayer format offers correct VGA (640x480)
resolution, but bad QQVGA (160x120). This last resolution is removed.
Signed-off-by: Jean-François Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>