HID: wacom: fix crash in wacom_aes_battery_handler()

Commit fd2a9b29dc9c ("HID: wacom: Remove AES power_supply after extended
inactivity") introduced wacom_aes_battery_handler() which is scheduled
as a delayed work (aes_battery_work).

In wacom_remove(), aes_battery_work is not canceled. Consequently, if
the device is removed while aes_battery_work is still pending, then hard
crashes or "Oops: general protection fault..." are experienced when
wacom_aes_battery_handler() is finally called. E.g., this happens with
built-in USB devices after resume from hibernate when aes_battery_work
was still pending at the time of hibernation.

So, take care to cancel aes_battery_work in wacom_remove().

Fixes: fd2a9b29dc9c ("HID: wacom: Remove AES power_supply after extended inactivity")
Signed-off-by: Thomas Zeitlhofer <[e-mail]>
Acked-by: Ping Cheng <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

drivers/hid/wacom_sys.c

···
 	hid_hw_stop(hdev);
 
 	cancel_delayed_work_sync(&wacom->init_work);
+	cancel_delayed_work_sync(&wacom->aes_battery_work);
 	cancel_work_sync(&wacom->wireless_work);
 	cancel_work_sync(&wacom->battery_work);
 	cancel_work_sync(&wacom->remote_work);