usb: check page select value while processing iTD

While processing isochronous transfer descriptors(iTD), the page
select(PG) field value could lead to an OOB read access. Add
check to avoid it.

Reported-by: Qinghao Tang <luodalongde@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-id: 1453233406-12165-1-git-send-email-ppandit@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
