staging: comedi: refactor cb_pcidda driver and use module_comedi_pci_driver

staging: comedi: refactor cb_pcidda driver and use module_comedi_pci_driver

Move the module_init/module_exit routines and the associated
struct comedi_drive and struct pci_driver to the end of the
source. This is more typical of how other drivers are written
and removes the need for the forward declarations.

Convert the driver to use the module_comedi_pci_driver() macro
which makes the code smaller and a bit simpler.

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