net_sched: remove warning from qdisc_hash_add

net_sched: remove warning from qdisc_hash_add

It was added in commit c09d3fe05666 ("pkt_sched: set root qdisc
before change() in attach_default_qdiscs()") to hide duplicates
from "tc qdisc show" for incative deivices.

After f7729dc48 ("net: sched: convert qdisc linked list to hashtable")
it triggered when classful qdisc is added to inactive device because
default qdiscs are added before switching root qdisc.

Anyway after commit cd430176cd95 ("net: sched: avoid duplicates in
qdisc dump") duplicates are filtered right in dumper.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>