net: sched: extend action ops with put_dev callback

As a preparation for removing dependency on rtnl lock from rules update
path, all users of shared objects must take reference while working with
them.

Extend action ops with put_dev() API to be used on net device returned by
get_dev().

Modify mirred action (only action that implements get_dev callback):
- Take reference to net device in get_dev.
- Implement put_dev API that releases reference to net device.

Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/act_api.h

@@ -101,6 +101,7 @@ struct tc_action_ops {
 	void	(*stats_update)(struct tc_action *, u64, u32, u64);
 	size_t  (*get_fill_size)(const struct tc_action *act);
 	struct net_device *(*get_dev)(const struct tc_action *a);
+	void	(*put_dev)(struct net_device *dev);
 	int     (*delete)(struct net *net, u32 index);
 };