V4L/DVB (13870): gspca - zc3xx: Bad detection of sensor HV7131R(c).

The webcam 0ac8:303b may have the sensors HV7131B or HV7131R(c).
This changeset checks the HV7131 type.

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