[NETFILTER]: x_tables: replace IPv4 DSCP target by address family independent version

This replaces IPv4 DSCP target by address family independent version.
This also
	- utilizes dsfield.h to get/mangle DS field in IPv4/IPv6 header
	- fixes Kconfig help text.

Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 0b8a70c..a74be49 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -25,6 +25,7 @@
 # targets
 obj-$(CONFIG_NETFILTER_XT_TARGET_CLASSIFY) += xt_CLASSIFY.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_CONNMARK) += xt_CONNMARK.o
+obj-$(CONFIG_NETFILTER_XT_TARGET_DSCP) += xt_DSCP.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_MARK) += xt_MARK.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_NFQUEUE) += xt_NFQUEUE.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_NOTRACK) += xt_NOTRACK.o