staging: comedi: update adl_pci7296 driver

Currently this driver only supports the 96-channel PCI-7296.
The 24 and 48 channel PCI-7224 and PCI-7248 boards share the
same register map and just have less 8255 devices providing
the i/o channels.

This adds the PCI PnP support for the other boards in the
ADLink PCI-72xx series.

Also, remove the legacy attach using the comedi_config utility.
This driver now supports the comedi PCI auto config attach
mechanism and the legacy attach is not supported or required
by this driver.

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>