[media] tda9875: remove duplicate driver

In commit 411674fd the tda9875 support was
added to tvaudio. This means that tda9875 is no longer used since mid-2009.

If there are out-of-tree users of this driver, then they can switch to tvaudio
instead.

The original commit message read as follows:

    This change allows bttv to use tvaudio for this device. Since this device
    has the same i2c address as the tda9874 we need to support both in the same
    tvaudio driver. This makes it possible for tvaudio to detect which chip is
    used. Originally the tda9875 was only available in the dedicated tda9875
    driver, but that makes life very hard for bttv since loading tvaudio might
    misdetect a tda9875 as a tda9874.

So there were good reasons for moving the tda9875 code into tvaudio.

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