net: hsr: remove synchronize_rcu() from hsr_add_port()

A synchronize_rcu() was added by mistake in commit
c5a7591 ("net/hsr: Use list_head (and rcu) instead
of array for slave devices.")

RCU does not mandate to observe a grace period after
list_add_tail_rcu().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250107144701.503884-1-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: edumazet

net/hsr/hsr_slave.c

@@ -204,7 +204,6 @@ int hsr_add_port(struct hsr_priv *hsr, struct net_device *dev,
 	}
 
 	list_add_tail_rcu(&port->port_list, &hsr->ports);
-	synchronize_rcu();
 
 	master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
 	netdev_update_features(master->dev);