hid: cp2112: Fix duplicate workqueue initialization

Previously the cp2112 driver called INIT_DELAYED_WORK within
cp2112_gpio_irq_startup, resulting in duplicate initilizations of the
workqueue on subsequent IRQ startups following an initial request. This
resulted in a warning in set_work_data in workqueue.c, as well as a rare
NULL dereference within process_one_work in workqueue.c.

Initialize the workqueue within _probe instead.

Fixes: 13de9cca ("HID: cp2112: add IRQ chip handling")
Signed-off-by: Danny Kaehn <danny.kaehn@plexus.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>