bnxt_en: Implement .set_port / .unset_port UDP tunnel callbacks

As per the new udp tunnel framework, drivers which need to know the
details of a port entry (i.e. port type) when it gets deleted should
use the .set_port / .unset_port callbacks.

Implementing the current .udp_tunnel_sync callback would mean that the
deleted tunnel port entry would be all zeros.  This used to work on
older firmware because it would not check the input when deleting a
tunnel port.  With newer firmware, the delete will now fail and
subsequent tunnel port allocation will fail as a result.

Fixes: 442a35a5

 ("bnxt: convert to new udp_tunnel_nic infra")
Reviewed-by: Kalesh Anakkur Purayil <kalesh-anakkur.purayil@broadcom.com>
Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>