scsi: scsi_ioctl: Return error code when blk_rq_map_kern() fails

The callers of sg_scsi_ioctl() already check for negative return values, so
we can drop the usage of DRIVER_ERROR and return the error from
blk_rq_map_kern() instead.

Link: https://lore.kernel.org/r/20210427083046.31620-3-hare@suse.deReviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

block/scsi_ioctl.c

@@ -484,9 +484,10 @@ int sg_scsi_ioctl(struct request_queue *q, struct gendisk *disk, fmode_t mode,
 		break;
 	}
 
-	if (bytes && blk_rq_map_kern(q, rq, buffer, bytes, GFP_NOIO)) {
-		err = DRIVER_ERROR << 24;
-		goto error;
+	if (bytes) {
+		err = blk_rq_map_kern(q, rq, buffer, bytes, GFP_NOIO);
+		if (err)
+			goto error;
 	}
 
 	blk_execute_rq(disk, rq, 0);