net: use jiffies_to_msecs to replace EXPIRES_IN_MS in inet/sctp_diag

EXPIRES_IN_MS macro comes from net/ipv4/inet_diag.c and dates
back to before jiffies_to_msecs() has been introduced.

Now we can remove it and use jiffies_to_msecs().

Suggested-by: Jakub Sitnicki <jkbs@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Jakub Sitnicki <jkbs@redhat.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>