Staging: comedi: add pci and usb wrapper header files

This are used by usb and pci comedi drivers to handle the different
kernel versions.  They will be eventually removed, but are needed now
to be able to add comedi drivers to the tree.

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>