vdpa/mlx5: Set err = -ENOMEM in case dma_map_sg_attrs fails

Set err = -ENOMEM if dma_map_sg_attrs() fails so the function reutrns
error.

Fixes: 94abbccd ("vdpa/mlx5: Add shared memory registration code")
Signed-off-by: Eli Cohen <elic@nvidia.com>
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20210411083646.910546-1-elic@nvidia.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

drivers/vdpa/mlx5/core/mr.c

@@ -278,8 +278,10 @@ static int map_direct_mr(struct mlx5_vdpa_dev *mvdev, struct mlx5_vdpa_direct_mr
 	mr->log_size = log_entity_size;
 	mr->nsg = nsg;
 	mr->nent = dma_map_sg_attrs(dma, mr->sg_head.sgl, mr->nsg, DMA_BIDIRECTIONAL, 0);
-	if (!mr->nent)
+	if (!mr->nent) {
+		err = -ENOMEM;
 		goto err_map;
+	}
 
 	err = create_direct_mr(mvdev, mr);
 	if (err)