staging: comedi: addi_common: move module init code to EOF

Move the module_{init,exit} code and associated variables to the end
of the file.

Use module_comedi_pci_driver() to remove the module init boilerplate.

For aesthetic reasons, rename the comedi_driver and pci_driver from
driver_* to *_driver.

Remove the forward declarations for i_ADDI_{Attach,Detach}.

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