Staging: comedi: add amplc_pci224 driver

Driver for Amplicon PCI224 and PCI234 AO boards

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