power: supply: cw2015: Fix potential null-ptr-deref in cw_bat_probe()

In the Linux kernel, the following vulnerability has been resolved: power: supply: cw2015: Fix potential null-ptr-deref in cw_bat_probe() cw_bat_probe() calls create_singlethread_workqueue() and not checked the ret value, which may return NULL. And a null-ptr-deref may happen: cw_bat_probe() create_singlethread_workqueue() # failed, cw_bat->wq is NULL queue_delayed_work() queue_delayed_work_on() __queue_delayed_work() # warning here, but continue __queue_work() # access wq->flags, null-ptr-deref Check the ret value and return -ENOMEM if it is NULL.