netfilter: ipset: timeout fixing bug broke SET target special timeout value

commit a73f89a61f92b364f0b4a3be412b5b70553afc23 upstream.

The patch "127f559 netfilter: ipset: fix timeout value overflow bug"
broke the SET target when no timeout was specified.

Reported-by: Jean-Philippe Menil <jean-philippe.menil@univ-nantes.fr>
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: David Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>