cciss: add cciss driver sysfs entries

Add sysfs entries to the cciss driver needed for the dm/multipath tools.

A file for vendor, model, rev, and unique_id is added for each logical
drive under directory /sys/bus/pci/devices/<dev>/ccissX/cXdY.  Where X =
the controller (or host) number and Y is the logical drive number.

A link from /sys/bus/pci/devices/<dev>/ccissX/cXdY/block:cciss!cXdY to
/sys/block/cciss!cXdY/device is also created.  A bus is created in
/sys/bus/cciss.  A link is created from the pci ccissX entry to
/sys/bus/cciss/devices/ccissX.  Please consider this for inclusion.

Signed-off-by: Mike Miller <mike.miller@hp.com>
Cc: Stephen M. Cameron <scameron@beardog.cca.cpqcorp.net>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>