netfilter: nf_conntrack: add nf_ct_kill()

Encapsulate the common

	if (del_timer(&ct->timeout))
		ct->timeout.function((unsigned long)ct)

sequence in a new function.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/netfilter/nf_conntrack_proto_icmp.c b/net/ipv4/netfilter/nf_conntrack_proto_icmp.c
index 78ab19a..0e21a46 100644
--- a/net/ipv4/netfilter/nf_conntrack_proto_icmp.c
+++ b/net/ipv4/netfilter/nf_conntrack_proto_icmp.c
@@ -87,9 +87,8 @@
 	   means this will only run once even if count hits zero twice
 	   (theoretically possible with SMP) */
 	if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
-		if (atomic_dec_and_test(&ct->proto.icmp.count)
-		    && del_timer(&ct->timeout))
-			ct->timeout.function((unsigned long)ct);
+		if (atomic_dec_and_test(&ct->proto.icmp.count))
+			nf_ct_kill(ct);
 	} else {
 		atomic_inc(&ct->proto.icmp.count);
 		nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);