Staging: comedi: usbdux[fast] firmware upload changes

usbdux and usbduxfast upload now their firmware via the firmware kernel
meachanism. No udev rules are needed for that except the default ones.
The firmware will usually be loaded from /lib/firmware. Upload via
comedi_config is still possible for static comedi devices
(comedi_num_legacy_minors>0).

Frank, thanks for the example code which sped up rewriting of the code
substantially.

From: Bernd Porr <BerndPorr@f2s.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Frank Mori Hess <fmhess@users.sourceforge.net>
Cc: David Schleef <ds@schleef.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>