netfilter: ctnetlink: fix wrong message type in user updates

This patch fixes the wrong message type that are triggered by
user updates, the following commands:

(term1)# conntrack -I -p tcp -s 1.1.1.1 -d 2.2.2.2 -t 10 --sport 10 --dport 20 --state LISTEN
(term1)# conntrack -U -p tcp -s 1.1.1.1 -d 2.2.2.2 -t 10 --sport 10 --dport 20 --state SYN_SENT
(term1)# conntrack -U -p tcp -s 1.1.1.1 -d 2.2.2.2 -t 10 --sport 10 --dport 20 --state SYN_RECV

only trigger event message of type NEW, when only the first is NEW
while others should be UPDATE.

(term2)# conntrack -E
    [NEW] tcp      6 10 LISTEN src=1.1.1.1 dst=2.2.2.2 sport=10 dport=20 [UNREPLIED] src=2.2.2.2 dst=1.1.1.1 sport=20 dport=10 mark=0
    [NEW] tcp      6 10 SYN_SENT src=1.1.1.1 dst=2.2.2.2 sport=10 dport=20 [UNREPLIED] src=2.2.2.2 dst=1.1.1.1 sport=20 dport=10 mark=0
    [NEW] tcp      6 10 SYN_RECV src=1.1.1.1 dst=2.2.2.2 sport=10 dport=20 [UNREPLIED] src=2.2.2.2 dst=1.1.1.1 sport=20 dport=10 mark=0

This patch also removes IPCT_REFRESH from the bitmask since it is
not of any use.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>