staging: comedi: ni_660x: use module_comedi_pci_driver()

Use the macro `module_comedi_pci_driver(comedi_driver, pci_driver)` to
register the module as a Comedi PCI driver.  Rename variables and
functions that have prefix `driver_` for consistency.  Set the `name`
member of the `struct pci_driver` variable in its initializer instead of
initializing it in the module initialization function.

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