net: dsa: fix dsa_tree_setup error path

Since the blamed commit, dsa_tree_teardown_switches() was split into two
smaller functions, dsa_tree_teardown_switches and dsa_tree_teardown_ports.

However, the error path of dsa_tree_setup stopped calling dsa_tree_teardown_ports.

Fixes: a57d8c21 ("net: dsa: flush switchdev workqueue before tearing down CPU/DSA ports")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dsa/dsa2.c

@@ -1089,6 +1089,7 @@ static int dsa_tree_setup(struct dsa_switch_tree *dst)
 teardown_master:
 	dsa_tree_teardown_master(dst);
 teardown_switches:
+	dsa_tree_teardown_ports(dst);
 	dsa_tree_teardown_switches(dst);
 teardown_cpu_ports:
 	dsa_tree_teardown_cpu_ports(dst);