[media] dabusb: remove obsolete driver

The dabusb driver was conceived as an experimental driver for a test
device. The driver never supported any shipped product, and, while
there were some updates for it in 2003, for an ancient product,
those changes were never submitted upstream.

Also, there's no DocBook for its API, nor any upstream discussion.

So it was decided to remove it in 2.6.39. Future support for a DAB API
should be discussed on the linux-media list first.

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