bridge: br_stp: Use built-in RCU list checking

list_for_each_entry_rcu() has built-in RCU and lock checking.

Pass cond argument to list_for_each_entry_rcu() to silence
false lockdep warning when CONFIG_PROVE_RCU_LIST is enabled
by default.

Signed-off-by: Madhuparna Bhowmik <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/bridge/br_stp.c

···
 {
 	struct net_bridge_port *p;
 
-	list_for_each_entry_rcu(p, &br->port_list, list) {
+	list_for_each_entry_rcu(p, &br->port_list, list,
+				lockdep_is_held(&br->lock)) {
 		if (p->port_no == port_no)
 			return p;
 	}