The dynamically allocted collection stack does not get freed in
all situations. Make sure to also free the collection stack when
using the parser in hid_open_report().

Fixes: 08a8a7cf ("HID: core: do not upper bound the collection stack")
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>