scsi: fs: remove exofs

This was an example for using the SCSI OSD protocol, which we're trying
to remove.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>