V4L/DVB (11279): bttv: tda9875 is no longer used by bttv, so remove from bt8xx/Kconfig.

Since tda9875 support was merged into tvaudio the bttv driver no
longer needs tda9875 as helper driver.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>