Staging: comedi: add c6xdigio driver

Driver for Mechatronic Systems Inc. C6x_DIGIO DSP daughter card

Written by Dan Block, email address unknown

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