ehci: Don't verify the next pointer for periodic qh-s and qtd-s

While testing the move to async packet handling for interrupt endpoints I
noticed that Windows-XP likes to play tricks with the next pointer for
periodic qh-s, so we should not fail qh / qtd verification when it changes.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
