kbuild: Link netfilter from parent dirs

No reason to link the netfilter subdirs from net/ instead of
net/ipv[46], the result looks just cleaner ;)

net/Makefile

@@ -13,16 +13,8 @@ obj-y	:= socket.o core/
 
 obj-$(CONFIG_NET)		+= ethernet/ 802/ sched/ netlink/
 obj-$(CONFIG_INET)		+= ipv4/
-obj-$(CONFIG_NETFILTER)		+= ipv4/netfilter/
 obj-$(CONFIG_UNIX)		+= unix/
 obj-$(CONFIG_IPV6)		+= ipv6/
-
-ifneq ($(CONFIG_IPV6),n)
-ifneq ($(CONFIG_IPV6),)
-obj-$(CONFIG_NETFILTER)		+= ipv6/netfilter/
-endif
-endif
-
 obj-$(CONFIG_KHTTPD)		+= khttpd/
 obj-$(CONFIG_PACKET)		+= packet/
 obj-$(CONFIG_NET_SCHED)		+= sched/

net/ipv4/Makefile

@@ -18,5 +18,6 @@ obj-$(CONFIG_NET_IPIP) += ipip.o
 obj-$(CONFIG_NET_IPGRE) += ip_gre.o
 obj-$(CONFIG_SYN_COOKIES) += syncookies.o
 obj-$(CONFIG_IP_PNP) += ipconfig.o
+obj-$(CONFIG_NETFILTER)	+= netfilter/
 
 include $(TOPDIR)/Rules.make

net/ipv6/Makefile

@@ -13,5 +13,6 @@ ipv6-objs :=	af_inet6.o ip6_output.o ip6_input.o addrconf.o sit.o \
 		ip6_flowlabel.o ipv6_syms.o
 
 #obj-$(CONFIG_IPV6_FIREWALL) += ip6_fw.o
+obj-$(CONFIG_NETFILTER)	+= netfilter/
 
 include $(TOPDIR)/Rules.make