sepolicy: new label for io scheduler sysfs nodes

* needed for io scheduler in performance settings

Change-Id: I818340ed62e3e1dd2674b93340b31723c7a985f4
diff --git a/sepolicy/system_app.te b/sepolicy/system_app.te
index 6ebd1ea..6c0e059 100644
--- a/sepolicy/system_app.te
+++ b/sepolicy/system_app.te
@@ -1,2 +1,3 @@
 # For performance settings
 allow system_app sysfs_devices_system_cpu:file rw_file_perms;
+allow system_app sysfs_devices_system_iosched:file rw_file_perms;