[NETLINK]: Reserve NETLINK_NETFILTER.

#define NETLINK_AUDIT		9	/* auditing */

#define NETLINK_FIB_LOOKUP	10	

#define NETLINK_ROUTE6		11	/* af_inet6 route comm channel */

#define NETLINK_NETFILTER	12	/* netfilter subsystem */

#define NETLINK_IP6_FW		13

#define NETLINK_DNRTMSG		14	/* DECnet routing messages */

#define NETLINK_KOBJECT_UEVENT	15	/* Kernel messages to userspace */