[NET]: Fix prio_tune() handling of root qdisc.

Fix the check in prio_tune() to see if sch->parent is TC_H_ROOT instead of
sch->handle to load or reject the qdisc for multiqueue devices.

Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>