Respect what the caller passed to ovs_tunnel_get_egress_info.

Fixes: 8f0aad6f ("openvswitch: Extend packet attribute for egress tunnel info")
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>