[media] gspca - zc3xx: Do automatic transfer control for hv7131r and pas202b

The bridge register 11 reports the current transfer status.
This value is used to know about a possible overflow and to adjust
the transfer parameters (registers 07 and 08).

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