As people are using scsi_debug to simulate a large
number of disks to play with the dev_t expansion,
some problems have come to light.

Changelog:
   - change num_devs to num_tgts
       so now the user can independently modify the
       number of hosts (add_host), the number of targets
       per host (num_tgts) and the number of luns per
       target (max_luns)
   - num_tgts sets scsi_host::max_id after allowance is
     made for the initiator's target id
   - max_luns default changed to 1 and it is sysfs
     writeable
   - REPORT LUN response cleaned up. Could now possibly
     generate a response indicatimg there were up to
     16,384 logical units available
   - clean up sense buffer generation

Updated http://www.torque.net/sg/sdebug25.html