V4L/DVB (7399): Removes video_dev from tuner-xc2028 config struct

The video_dev parameter, on tuner-xc2028 were used to pass i2c private data to
tuner_callback. Since the driver already have a pointer to i2c_adap->algo_data,
uses this instead.

This parameter were used also as a magic number to idenfity if two drivers are
trying to register the same xc3028 tuner. This occurs with boards with DVB
support, where both DVB and V4L drivers will share the same tuner.

Instead of using the algo_data as a private number, after this patch, the
driver will use i2c_adap->dev, with seems more consistent.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>