net/sched: act_tunnel_key: Remove rcu_read_lock protection

Remove rcu_read_lock protection from tunnel_key_dump and use
rtnl_dereference, dump operation is protected by  rtnl lock.

Also, remove rcu_read_lock from tunnel_key_release and use
rcu_dereference_protected.

Both operations are running exclusively and a writer couldn't modify
t->params while those functions are executed.

Fixes: 54d94fd89d90 ('net/sched: Introduce act_tunnel_key')
Signed-off-by: Hadar Hen Zion <hadarh@mellanox.com>
Acked-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>