ip6tnl/rtnl: add IFLA_IPTUN_PROTO on dump

IPv6 tunnels can have three mode: 4in6, 6in6 and xin6.
This information was missing in the netlink message.

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 c1bf0b5..f5ea6b7 100644
--- a/include/uapi/linux/if_tunnel.h
+++ b/include/uapi/linux/if_tunnel.h
@@ -47,6 +47,7 @@
 	IFLA_IPTUN_ENCAP_LIMIT,
 	IFLA_IPTUN_FLOWINFO,
 	IFLA_IPTUN_FLAGS,
+	IFLA_IPTUN_PROTO,
 	__IFLA_IPTUN_MAX,
 };
 #define IFLA_IPTUN_MAX	(__IFLA_IPTUN_MAX - 1)