qed: Fix an error code qed_ll2_start_xmit()

We accidentally deleted the code to set "rc = -ENOMEM;" and this patch
adds it back.

Fixes: d2201a2159 ("qed: No need for LL2 frags indication")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/qlogic/qed/qed_ll2.c

@@ -2496,6 +2496,7 @@ static int qed_ll2_start_xmit(struct qed_dev *cdev, struct sk_buff *skb,
 		if (unlikely(dma_mapping_error(&cdev->pdev->dev, mapping))) {
 			DP_NOTICE(cdev,
 				  "Unable to map frag - dropping packet\n");
+			rc = -ENOMEM;
 			goto err;
 		}