V4L/DVB (4068): Removed all references to kernel stuff from videodev.h and videodev2.h

The videodev.h and videodev2.h describe the public API for V4L and V4L2.
It shouldn't have there any kernel-specific stuff. Those were moved to
v4l2-dev.h.
This patch removes some uneeded headers and include v4l2-common.h on all
V4L driver. This header includes device implementation of V4L2 API provided
on v4l2-dev.h as well as V4L2 internal ioctls that provides connections
between master driver and its i2c devices.

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