[NET_SCHED]: Fix ingress locking

Ingress queueing uses a seperate lock for serializing enqueue operations,
but fails to properly protect itself against concurrent changes to the
qdisc tree. Use queue_lock for now since the real fix it quite intrusive.

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