V4L/DVB (6586): Remove some dead code and make drive fully V4L2 compatible

There were some vestiges of an old V4L1 I2C driver that were called by em28xx.
This patch removes this dead code, and replaces videodev.h to videodev2.h

Now, this driver doesn't require V4L1 anymore.

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