[media] gspca - zc3xx: Adjust the JPEG decompression tables

As the bridge register 08 defines the JPEG compression quality,
it must be changed on JPEG quality change and also, the decompression
tables must be adjusted when the register varies.

[mchehab@redhat.com: replace a // comment by a /* */ one]
Signed-off-by: Jean-François Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>