staging: comedi: amplc_dio200: support PCIe215, PCIe236 and PCIe296

Add preliminary support for the above PCIe boards.  The interrupt
subdevice is not working yet as the boards need some additional
initialization to enable interrupts.  Reserve an unused subdevice that
will eventually become a timer subdevice.

Some unused subdevices have been added between the used subdevices on
the PCIe215 and PCIe236.  This is so the subdevice numbers will match a
pattern-matching feature to be added at a later date, where the
pattern-match specifications for a subdevice include pattern-match
results from other subdevices, specified by index.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>