scsi: core: Remove OSD include files

All code from which the OSD include files were included has been removed.
Hence also remove the include files themselves. See also commit
19fcae3d ("scsi: remove the SCSI OSD library").

Cc: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>