This small patch adds a "release" method to the "pseudo_0"
device to stop the noise when the scsi_debug module is
loaded.

Another annoyance that I was unable to get to the bottom
of was during "rmmod scsi_debug" **:
  Synchronizing SCSI cache for disk sda: <4>FAILED
    status = 0, message = 00, host = 1, driver = 00
That is a DID_NO_CONNECT error. So the LLD host is
being shut down before the sd driver gets a chance to
send through a SYNCHRONIZE CACHE command. If the user
instigates a rmmod (as distinct from the hardware
saying the host/device is gone), shouldn't a window
be left open for such a flushing type command. This
problem seems to have appeared recently.


** "echo -1 > add_host" in scsi_debug's driver directory
   (i.e. remove a host) also causes the same error so the
   problem is not perculiar to rmmod.