V4L/DVB (11040): gspca - most jpeg subdrivers: Have the JPEG quality settable.

The JPEG quality of the images (quantization tables) is now settable by the
VIDIOC_S_JPEGCOMP ioctl.

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