e1000e: Add missing dma_mapping_error-call in e1000_alloc_jumbo_rx_buffers

After dma_map_page, dma_mapping_error must be called. It seems safe to
not free the skb/page allocated in this function, as the skb/page can be
reused later.
Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/e1000e/netdev.c

@@ -848,11 +848,16 @@ static void e1000_alloc_jumbo_rx_buffers(struct e1000_ring *rx_ring,
 			}
 		}
 
-		if (!buffer_info->dma)
+		if (!buffer_info->dma) {
 			buffer_info->dma = dma_map_page(&pdev->dev,
 			                                buffer_info->page, 0,
 			                                PAGE_SIZE,
 							DMA_FROM_DEVICE);
+			if (dma_mapping_error(&pdev->dev, buffer_info->dma)) {
+				adapter->alloc_rx_buff_failed++;
+				break;
+			}
+		}
 
 		rx_desc = E1000_RX_DESC_EXT(*rx_ring, i);
 		rx_desc->read.buffer_addr = cpu_to_le64(buffer_info->dma);