HID: usbhid: cancel timer for retry synchronously

This makes sure IO is never restarted while a reset is going on

In particular there seems to be no protection from hid_retry_timeout() calling
hid_start_in() which would start IO after hid_pre_reset() has already called
hid_cease_io() because that uses del_timer(), not del_timer_sync()

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>