bq27x00_battery: Fix OOPS caused by unregistring bq27x00 driver

* power_supply_unregister call bq27x00_battery_get_property which
  call bq27x00_battery_poll
* make sure that bq27x00_battery_poll will not call
  schedule_delayed_work again after unregister (which cause OOPS)

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>

drivers/power/bq27x00_battery.c

@@ -598,6 +598,14 @@ static int bq27x00_powersupply_init(struct bq27x00_device_info *di)
 
 static void bq27x00_powersupply_unregister(struct bq27x00_device_info *di)
 {
+	/*
+	 * power_supply_unregister call bq27x00_battery_get_property which
+	 * call bq27x00_battery_poll.
+	 * Make sure that bq27x00_battery_poll will not call
+	 * schedule_delayed_work again after unregister (which cause OOPS).
+	 */
+	poll_interval = 0;
+
 	cancel_delayed_work_sync(&di->work);
 
 	power_supply_unregister(&di->bat);