[NETFILTER]: CLUSTERIP: fix memcpy() length typo

Fix a trivial typo in clusterip_config_init().

Signed-off-by: KOVACS Krisztian <hidden@balabit.hu>
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>