net/mlx4: Fix error check for dma_map_sg

dma_map_sg return 0 on error.
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/r/20220825063533.21015-1-jinpu.wang@ionos.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mellanox/mlx4/icm.c

@@ -208,7 +208,7 @@ struct mlx4_icm *mlx4_alloc_icm(struct mlx4_dev *dev, int npages,
 						chunk->sg, chunk->npages,
 						DMA_BIDIRECTIONAL);
 
-			if (chunk->nsg <= 0)
+			if (!chunk->nsg)
 				goto fail;
 		}
 
@@ -222,7 +222,7 @@ struct mlx4_icm *mlx4_alloc_icm(struct mlx4_dev *dev, int npages,
 		chunk->nsg = dma_map_sg(&dev->persist->pdev->dev, chunk->sg,
 					chunk->npages, DMA_BIDIRECTIONAL);
 
-		if (chunk->nsg <= 0)
+		if (!chunk->nsg)
 			goto fail;
 	}