[media] gspca - zc3xx: Fix bad images with the sensor hv7131r

The problem was introduced by the commit 2af0b4c6.
Some registers were no more initialized.

Tested-by: &lt;Giovanni Scafora <giovanni@archlinux.org>
Tested-by: &lt;Sergey Manucharian <sm@ingeniware.com>
Signed-off-by: Jean-François Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>