sch_mqprio: Fix build with older gcc.

  CC [M]  net/sched/sch_mqprio.o
net/sched/sch_mqprio.c: In function ?mqprio_init?:
net/sched/sch_mqprio.c:145: error: unknown field ?tc? specified in initializer
net/sched/sch_mqprio.c:145: warning: missing braces around initializer
net/sched/sch_mqprio.c:145: warning: (near initialization for ?tc.<anonymous>?)
make[2]: *** [net/sched/sch_mqprio.o] Error 1
make[1]: *** [net/sched] Error 2
make: *** [net] Error 2

Several people reported this, surround the unnamed union
member initialization with braces to fix.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sched/sch_mqprio.c

@@ -142,7 +142,7 @@ static int mqprio_init(struct Qdisc *sch, struct nlattr *opt)
 	 */
 	if (qopt->hw) {
 		struct tc_to_netdev tc = {.type = TC_SETUP_MQPRIO,
-					  .tc = qopt->num_tc};
+					  { .tc = qopt->num_tc }};
 
 		priv->hw_owned = 1;
 		err = dev->netdev_ops->ndo_setup_tc(dev, sch->handle, 0, &tc);