cx88: fix: don't duplicate xc4000 entry for radio

commit b6854e3f upstream.

All radio tuners in cx88 driver using same address for radio and tuner,
so there is no need to probe it twice for same tuner and we can use
radio_type UNSET, this also fix broken radio since kernel 2.6.39-rc1
for those tuners.

Signed-off-by: Miroslav Slugen <thunder.mmm@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>