nfp: flower: fix for take a mutex lock in soft irq context and rcu lock

The neighbour event callback call the function nfp_tun_write_neigh,
this function will take a mutex lock and it is in soft irq context,
change the work queue to process the neighbour event.

Move the nfp_tun_write_neigh function out of range rcu_read_lock/unlock()
in function nfp_tunnel_request_route_v4 and nfp_tunnel_request_route_v6.

Fixes: abc21095

 ("nfp: flower: tunnel neigh support bond offload")
CC: stable@vger.kernel.org # 6.2+
Signed-off-by: Hui Zhou <hui.zhou@corigine.com>
Signed-off-by: Louis Peens <louis.peens@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>