V4L/DVB (10107): More than one driver defines the same var name (dump_bridge). Add

"static" on stv06xx for all static functions and parameters to avoid
such troubles.

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