staging: comedi: usbduxsigma: use module_comedi_usb_driver()

staging: comedi: usbduxsigma: use module_comedi_usb_driver()

Use the module_comedi_usb_driver helper macro to initialize this
module. Rename the driver structs to follow the pattern of the
other comedi driver types and add some whitespace to improve
readability.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Frank Mori Hess <fmhess@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>