nfp: flower-ct: fix error return code in nfp_fl_ct_add_offload()

If nfp_tunnel_add_ipv6_off() fails, it should return error code
in nfp_fl_ct_add_offload().

Fixes: 5a2b930416 ("nfp: flower-ct: compile match sections of flow_payload")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Louis Peens <louis.peens@corigine.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/flower/conntrack.c

@@ -710,8 +710,10 @@ static int nfp_fl_ct_add_offload(struct nfp_fl_nft_tc_merge *m_entry)
 			dst = &gre_match->ipv6.dst;
 
 			entry = nfp_tunnel_add_ipv6_off(priv->app, dst);
-			if (!entry)
+			if (!entry) {
+				err = -ENOMEM;
 				goto ct_offload_err;
+			}
 
 			flow_pay->nfp_tun_ipv6 = entry;
 		} else {
@@ -760,8 +762,10 @@ static int nfp_fl_ct_add_offload(struct nfp_fl_nft_tc_merge *m_entry)
 			dst = &udp_match->ipv6.dst;
 
 			entry = nfp_tunnel_add_ipv6_off(priv->app, dst);
-			if (!entry)
+			if (!entry) {
+				err = -ENOMEM;
 				goto ct_offload_err;
+			}
 
 			flow_pay->nfp_tun_ipv6 = entry;
 		} else {