pkt_sched: fix sparse warning

Impact: make global function static

Fix the following sparse warning:

net/sched/sch_api.c:192:14: warning: symbol 'qdisc_match_from_root' was not declared. Should it be static?

Signed-off-by: Hannes Eder <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/sched/sch_api.c

···
    (root qdisc, all its children, children of children etc.)
  */
 
-struct Qdisc *qdisc_match_from_root(struct Qdisc *root, u32 handle)
+static struct Qdisc *qdisc_match_from_root(struct Qdisc *root, u32 handle)
 {
 	struct Qdisc *q;