ipip/rtnl: add IFLA_IPTUN_PMTUDISC on dump

This parameter was missing in the dump.

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 f5ea6b7..5ab0c8d 100644
--- a/include/uapi/linux/if_tunnel.h
+++ b/include/uapi/linux/if_tunnel.h
@@ -48,6 +48,7 @@
 	IFLA_IPTUN_FLOWINFO,
 	IFLA_IPTUN_FLAGS,
 	IFLA_IPTUN_PROTO,
+	IFLA_IPTUN_PMTUDISC,
 	__IFLA_IPTUN_MAX,
 };
 #define IFLA_IPTUN_MAX	(__IFLA_IPTUN_MAX - 1)