fix unkillable reboot logging on tici

selfdrive/manager.py

@@ -353,7 +353,8 @@ def kill_managed_process(name):
         join_process(running[name], 15)
         if running[name].exitcode is None:
           cloudlog.critical("unkillable process %s failed to die!" % name)
-          os.system("date >> /sdcard/unkillable_reboot")
+          os.system("date >> /data/unkillable_reboot")
+          os.sync()
           HARDWARE.reboot()
           raise RuntimeError
       else: