openvswitch: Use regular VXLAN net_device device

openvswitch: Use regular VXLAN net_device device

This gets rid of all OVS specific VXLAN code in the receive and
transmit path by using a VXLAN net_device to represent the vport.
Only a small shim layer remains which takes care of handling the
VXLAN specific OVS Netlink configuration.

Unexports vxlan_sock_add(), vxlan_sock_release(), vxlan_xmit_skb()
since they are no longer needed.

Signed-off-by: Thomas Graf <[email protected]>
Signed-off-by: Pravin B Shelar <[email protected]>
Signed-off-by: David S. Miller <[email protected]>