sit: allow to configure 6rd tunnels via netlink

This patch add the support of 6RD tunnels management via netlink.
Note that netdev_state_change() is now called when 6RD parameters are updated.

6RD parameters are updated only if there is at least one 6RD attribute.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/uapi/linux/if_tunnel.h b/include/uapi/linux/if_tunnel.h
index 5ab0c8d..aee73d0 100644
--- a/include/uapi/linux/if_tunnel.h
+++ b/include/uapi/linux/if_tunnel.h
@@ -49,6 +49,10 @@
 	IFLA_IPTUN_FLAGS,
 	IFLA_IPTUN_PROTO,
 	IFLA_IPTUN_PMTUDISC,
+	IFLA_IPTUN_6RD_PREFIX,
+	IFLA_IPTUN_6RD_RELAY_PREFIX,
+	IFLA_IPTUN_6RD_PREFIXLEN,
+	IFLA_IPTUN_6RD_RELAY_PREFIXLEN,
 	__IFLA_IPTUN_MAX,
 };
 #define IFLA_IPTUN_MAX	(__IFLA_IPTUN_MAX - 1)