net/sched: cls_matchall: Dump the classifier flags

The classifier flags are not dumped to user-space, do that.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Yotam Gigi <yotamg@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>