gtp: include role in link info

Querying link info for the GTP interface doesn't reveal in which "role" the
device is set to operate.  Include this information in the info query
result.
Signed-off-by: Jonas Bonn <jonas@norrbonn.se>
Acked-by: Harald Welte <laforge@gnumonks.org>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/gtp.c

@@ -728,7 +728,8 @@ static int gtp_validate(struct nlattr *tb[], struct nlattr *data[],
 
 static size_t gtp_get_size(const struct net_device *dev)
 {
-	return nla_total_size(sizeof(__u32));	/* IFLA_GTP_PDP_HASHSIZE */
+	return nla_total_size(sizeof(__u32)) + /* IFLA_GTP_PDP_HASHSIZE */
+		nla_total_size(sizeof(__u32)); /* IFLA_GTP_ROLE */
 }
 
 static int gtp_fill_info(struct sk_buff *skb, const struct net_device *dev)
@@ -737,6 +738,8 @@ static int gtp_fill_info(struct sk_buff *skb, const struct net_device *dev)
 
 	if (nla_put_u32(skb, IFLA_GTP_PDP_HASHSIZE, gtp->hash_size))
 		goto nla_put_failure;
+	if (nla_put_u32(skb, IFLA_GTP_ROLE, gtp->role))
+		goto nla_put_failure;
 
 	return 0;