[NETFILTER]: nf_conntrack/nf_nat: fix incorrect config ifdefs

The nf_conntrack_netlink config option is named CONFIG_NF_CT_NETLINK,
but multiple files use CONFIG_IP_NF_CONNTRACK_NETLINK or
CONFIG_NF_CONNTRACK_NETLINK for ifdefs.

Fix this and reformat all CONFIG_NF_CT_NETLINK ifdefs to only use a line.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>