scsi: osst: kill obsolete driver

The osst driver is becoming obsolete, as the manufacturer went out of
business ages ago, and the maintainer has no means of testing any
improvements anymore.  Plus these days flash drives are cheaper and offer a
higher capacity.  So drop it completely.

Cc: Willem Riede <osst@riede.org>
Signed-off-by: Hannes Reinece <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>