nfp: convert to new udp_tunnel_nic infra

NFP conversion is pretty straightforward. We want to be able
to sleep, and only get callbacks when the device is open.

NFP did not ask for port replay when ports were removed, now
new infra will provide this feature for free.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>