nfp: fix error return code in nfp_net_netdev_open()

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Fixes: 73725d9d ("nfp: allocate ring SW structs dynamically")
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Acked-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/nfp_net_common.c

@@ -2044,12 +2044,16 @@ static int nfp_net_netdev_open(struct net_device *netdev)
 
 	nn->rx_rings = kcalloc(nn->num_rx_rings, sizeof(*nn->rx_rings),
 			       GFP_KERNEL);
-	if (!nn->rx_rings)
+	if (!nn->rx_rings) {
+		err = -ENOMEM;
 		goto err_free_lsc;
+	}
 	nn->tx_rings = kcalloc(nn->num_tx_rings, sizeof(*nn->tx_rings),
 			       GFP_KERNEL);
-	if (!nn->tx_rings)
+	if (!nn->tx_rings) {
+		err = -ENOMEM;
 		goto err_free_rx_rings;
+	}
 
 	for (r = 0; r < nn->num_r_vecs; r++) {
 		err = nfp_net_prepare_vector(nn, &nn->r_vecs[r], r);