media: cpia2_usb: first wake up, then free in disconnect

Kasan reported a use after free in cpia2_usb_disconnect()
It first freed everything and then woke up those waiting.
The reverse order is correct.

Fixes: 6c493f8b

 ("[media] cpia2: major overhaul to get it in a working state again")

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Reported-by:  <syzbot+0c90fc937c84f97d0aa6@syzkaller.appspotmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>