This adds the v4l2 API to the linux kernel.

The first, original video4linux API has a number of design bugs.  They
are fixed in this new API revision.  It already exists for quite some
time.  Last weeks it got a number of cleanups based on the experiences
of the last years (drop stuff nobody uses, fix some inconsistencies).
We consider it being in a pretty good shape now and like to see it in
2.6.

This patch is basically the header file with all the structs and ioctls
in there.  A small module with some helper functions for v4l2 drivers is
included too.  Related updates (bttv, ...) will follow as separate
patches.