qcacmn: Add missing qdf_spinlock_destroy() to free debug cookie

Add missing qdf_spinlock_destroy() to destroy spin lock debug cookie
for SLUB build. For normal builds, qdf_spinlock_destroy() is a NO-OP
function.

Change-Id: If5a3843a468e460952dc64f0e6b5b1fba05ebbb3
CRs-Fixed: 2078940

qdf/linux/src/qdf_mc_timer.c

@@ -216,6 +216,7 @@ void qdf_mc_timer_manager_exit(void)
 {
 	qdf_timer_clean();
 	qdf_list_destroy(&qdf_timer_list);
+	qdf_spinlock_destroy(&qdf_timer_list_lock);
 }
 EXPORT_SYMBOL(qdf_mc_timer_manager_exit);
 #endif