net: sched: taprio: fix -Wmissing-prototypes warnings

We get one warnings when build kernel W=1:
net/sched/sch_taprio.c:1155:6: warning: no previous prototype for ‘taprio_offload_config_changed’ [-Wmissing-prototypes]

Make the function static to fix this.

Fixes: 9c66d156 ("taprio: Add support for hardware offloading")
Signed-off-by: NYi Wang <wang.yi59@zte.com.cn>
Acked-by: NVinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>

net/sched/sch_taprio.c

@@ -1152,7 +1152,7 @@ EXPORT_SYMBOL_GPL(taprio_offload_free);
  * offload state (PENDING, ACTIVE, INACTIVE) so it can be visible in dump().
  * This is left as TODO.
  */
-void taprio_offload_config_changed(struct taprio_sched *q)
+static void taprio_offload_config_changed(struct taprio_sched *q)
 {
 	struct sched_gate_list *oper, *admin;