net: bridge: Change a cleanup in br_multicast_new_port_group() to goto

This function is getting more to clean up in the following patches.
Structuring the cleanups in one labeled block will allow reusing the same
cleanup from several places.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_multicast.c

@@ -1309,8 +1309,7 @@ struct net_bridge_port_group *br_multicast_new_port_group(
 	    rhashtable_lookup_insert_fast(&port->br->sg_port_tbl, &p->rhnode,
 					  br_sg_port_rht_params)) {
 		NL_SET_ERR_MSG_MOD(extack, "Couldn't insert new port group");
-		kfree(p);
-		return NULL;
+		goto free_out;
 	}
 
 	rcu_assign_pointer(p->next, next);
@@ -1324,6 +1323,10 @@ struct net_bridge_port_group *br_multicast_new_port_group(
 		eth_broadcast_addr(p->eth_addr);
 
 	return p;
+
+free_out:
+	kfree(p);
+	return NULL;
 }
 
 void br_multicast_del_port_group(struct net_bridge_port_group *p)