ipvs: fix synchronization on connection close

commit 9d3a0de7 makes slaves expire as they would do on the master
with much shorter timeouts. But it introduces another problem:
When we close a connection, on master server the connection became
CLOSE_WAIT/TIME_WAIT, it was synced to slaves, but if master is
finished within it's timeouts (CLOSE), it will not be synced to
slaves. Then slaves will be kept on CLOSE_WAIT/TIME_WAIT until
timeout reaches. Thus we should also sync with CLOSE.

Cc: Wensong Zhang <wensong@linux-vs.org>
Cc: Simon Horman <horms@verge.net.au>
Cc: Julian Anastasov <ja@ssi.bg>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Xiaotian Feng <dfeng@redhat.com>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Patrick McHardy <kaber@trash.net>