staging: comedi: das08: separately configure ISA and PCI

The das08 driver supports both ISA and PCI cards, but currently is
configured outside the ISA and PCI comedi driver sections.  The module
is also used by the das08_cs driver.  This patch splits the
configuration to make the ISA and PCI parts separately selectable, and
changes the driver to only include the selected ISA and/or PCI board
types.  Also, if neither the ISA or PCI parts are selected, and the
module is only needed for the das08_cs driver, don't register the driver
as a comedi driver as it doesn't have any boards to support.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>