ACPI: battery: Fix possible crash when unregistering a battery hook

In the Linux kernel, the following vulnerability has been resolved: ACPI: battery: Fix possible crash when unregistering a battery hook When a battery hook returns an error when adding a new battery, then the battery hook is automatically unregistered. However the battery hook provider cannot know that, so it will later call battery_hook_unregister() on the already unregistered battery hook, resulting in a crash. Fix this by using the list head to mark already unregistered battery hooks as already being unregistered so that they can be ignored by battery_hook_unregister().