nf_conntrack_ecache.h: Fix missing braces

This patch add missing braces of today's net-next-2.6:
include/net/netfilter/nf_conntrack_ecache.h

Signed-off-by: Guo-Fu Tseng <cooldavid@cooldavid.org>
Signed-off-by: David S. Miller <davem@davemloft.net>