If usb_poll() isn't called fast enough, the UHCI controller marks an
underrun interrupt queue as done (terminating the queue at the head).
We can recover from this situation, when usb_poll() gets called again,
and the queue is processed.
Change-Id: Id56c9df44d6dbd53cd30ad89dfb5bf5977799829
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: http://review.coreboot.org/1898
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>