vxlan: allow a user to set TTL value

"ip link add ... type vxlan ... ttl X" allows a user to set the TTL
used by a VXLAN for encapsulation. The provided value was ignored by
vxlan module and the default value of 1 was used when encapsulating
multicast packets.
Signed-off-by: Vincent Bernat <bernat@luffy.cx>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vxlan.c

@@ -1107,6 +1107,9 @@ static int vxlan_newlink(struct net *net, struct net_device *dev,
 	if (data[IFLA_VXLAN_TOS])
 		vxlan->tos  = nla_get_u8(data[IFLA_VXLAN_TOS]);
 
+	if (data[IFLA_VXLAN_TTL])
+		vxlan->ttl = nla_get_u8(data[IFLA_VXLAN_TTL]);
+
 	if (!data[IFLA_VXLAN_LEARNING] || nla_get_u8(data[IFLA_VXLAN_LEARNING]))
 		vxlan->learn = true;