[media] gspca_zc3xx: Disable the highest quality setting as it is not usable

Even with BRC the highest quality setting is not usable, BRC strips so
much data from each MCU that the quality becomes worse then using a lower
quality setting to begin with.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>