MPTCP: fix lock class name family in pm_nl_create_listen_socket

MPTCP: fix lock class name family in pm_nl_create_listen_socket

In mptcp_pm_nl_create_listen_socket(), use entry->addr.family
instead of sk->sk_family for lock class setup. The 'sk' parameter
is a netlink socket, not the MPTCP subflow socket being created.

Fixes: cee4034a3db1 ("mptcp: fix lockdep false positive in mptcp_pm_nl_create_listen_socket()")
Signed-off-by: Li Xiasong <lixiasong1@huawei.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260319112159.3118874-1-lixiasong1@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>