Staging: comedi: add local copy of interrupt.h

This is needed for some internal comedi driver macros that were
built up over the years to handle multiple kernel versions.  It will be
removed eventually.

From: David Schleef <ds@schleef.org>
Cc: Frank Mori Hess <fmhess@users.sourceforge.net>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>