[NET_SCHED]: Remove unnecessary stats_lock pointers

Remove stats_lock pointers from qdisc-internal structures, in all cases
it points to dev->queue_lock. The only case where it is necessary is for
top-level qdiscs, where it might also point to dev->ingress_lock in case
of the ingress qdisc. Also remove it from actions completely, it always
points to the actions internal lock.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>