nvmet: Make dsm number of ranges zero based

This caused the nvmet request data length to be
incorrect.
Signed-off-by: Alexander Solganik <sashas@lightbitslabs.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/target/io-cmd.c

@@ -206,7 +206,7 @@ int nvmet_parse_io_cmd(struct nvmet_req *req)
 		return 0;
 	case nvme_cmd_dsm:
 		req->execute = nvmet_execute_dsm;
-		req->data_len = le32_to_cpu(cmd->dsm.nr) *
+		req->data_len = le32_to_cpu(cmd->dsm.nr + 1) *
 			sizeof(struct nvme_dsm_range);
 		return 0;
 	default: