netdev: Fix user space tunneling for set_tunnel action.

netdev: Fix user space tunneling for set_tunnel action.

e.g. Set tunnel id for encapsulated VxLAN packet (out_key=flow):

ovs-vsctl add-port int-br vxlan0 -- set interface vxlan0 \
    type=vxlan options:remote_ip=172.168.1.2 options:out_key=flow

ovs-ofctl add-flow int-br in_port=LOCAL, icmp,\
    actions=set_tunnel:3, output:1 (1 is the port# of vxlan0)

Output tunnel ID should be modified to 3 with this patch.

Signed-off-by: Ricky Li <ricky.li@intel.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>