staging: i4l: delete the whole thing

It's now 2017, and a new LTS kernel has been chosen, so let's do what we
said we would do in the TODO file and delete this code.  If it's still
needed, and a maintainer steps up to take it over, we will easily revert
it.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Karsten Keil <isdn@linux-pingi.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>