net: prevent possible UAF in rtnl_prop_list_size()

net: prevent possible UAF in rtnl_prop_list_size()

I was mistaken by synchronize_rcu() [1] call in netdev_name_node_alt_destroy(),
giving a false sense of RCU safety at delete times.

We have to use list_del_rcu() to not confuse potential readers
in rtnl_prop_list_size().

[1] This synchronize_rcu() call was later removed in commit 723de3ebef03
("net: free altname using an RCU callback").

Fixes: 9f30831390ed ("net: add rcu safety to rtnl_prop_list_size()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260502124102.499204-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>