mptcp: use the variable sk instead of open-coding

Since the local variable sk has been defined, use it instead of
open-coding.

Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Geliang Tang <geliangtang@gmail.com>

net/mptcp/pm_netlink.c

@@ -313,7 +313,7 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
  struct mptcp_pm_addr_entry *local;
  struct pm_nl_pernet *pernet;
 
- pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
+ pernet = net_generic(sock_net(sk), pm_nl_pernet_id);
 
  pr_debug("local %d:%d signal %d:%d subflows %d:%d\n",
  msk->pm.local_addr_used, msk->pm.local_addr_max,
@@ -399,7 +399,7 @@ void mptcp_pm_nl_add_addr_received(struct mptcp_sock *msk)
  local.family = remote.family;
 
  spin_unlock_bh(&msk->pm.lock);
- __mptcp_subflow_connect((struct sock *)msk, &local, &remote);
+ __mptcp_subflow_connect(sk, &local, &remote);
  spin_lock_bh(&msk->pm.lock);
 
  mptcp_pm_announce_addr(msk, &remote, true, use_port);