net_sched: notify filter deletion when deleting a chain

When we delete a chain of filters, we need to notify
user-space we are deleting each filters in this chain
too.

Fixes: 32a4f5ec ("net: sched: introduce chain object to uapi")
Cc: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>