net: Remove deprecated tunnel specific UDP offload functions

Now that we have all the drivers using udp_tunnel_get_rx_ports,
ndo_add_udp_enc_rx_port, and ndo_del_udp_enc_rx_port we can drop the
function calls that were specific to VXLAN and GENEVE.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>