datapath-windows: use correct dst port during Vxlan Tx

datapath-windows: use correct dst port during Vxlan Tx

A previous commit used the wrong DST port in the UDP header during Vxlan
Tx which caused Vxlan tunneling to break. Fixing it here..

Also included is a cosmetic fix in OvsDetectTunnelRxPkt() where we were
using htons() instead of ntohs(). Doesn't make a difference in practice
though.

One more change is, OvsIpHlprCbVxlan() has been nuked since it is not
used. Not sure if it is worth being resurrected.

Testing done: Ping across Vxlan tunnel and Stt tunnel.

Signed-off-by: Nithin Raju <nithin@vmware.com>
Reported-by: Eitan Eliahu <eliahue@vmware.com>
Acked-by: Alin Gabriel Serdean <aserdean@cloudbasesolutions.com>
Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>