V4L/DVB (8834): gspca: Have a bigger buffer for sn9c10x compressed images.

Under certain conditions sonixb compressed frame size can get bigger then
the uncompressed size (seen with 0c45:6028), so make the buffers slightly
bigger.

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>