udp_tunnel: hard-wire NDOs to udp_tunnel_nic_*_port() helpers

All drivers use udp_tunnel_nic_*_port() helpers, prepare for
NDO removal by invoking those helpers directly.

The helpers are safe to call on all devices, they check if
device has the UDP tunnel state initialized.

Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>