V4L/DVB (9094): gspca: Frame counter in ALi m5602.

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