netfilter: xtables: add device group match

Add a new 'devgroup' match to match on the device group of the
incoming and outgoing network device of a packet.

Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 1148643..d57a890 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -77,6 +77,7 @@
 obj-$(CONFIG_NETFILTER_XT_MATCH_CONNTRACK) += xt_conntrack.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_CPU) += xt_cpu.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_DCCP) += xt_dccp.o
+obj-$(CONFIG_NETFILTER_XT_MATCH_DEVGROUP) += xt_devgroup.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_DSCP) += xt_dscp.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_ESP) += xt_esp.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_HASHLIMIT) += xt_hashlimit.o