[PATCH] UHCI: Improve handling of iso TDs

The uhci-hcd driver is fairly lax about the way it handles isochronous
transfers.  This patch (as579) improves it in three respects:

	TDs for a new URB aren't added to the schedule until all of
	them have been allocated.  This way there's no risk of the
	controller executing some of them when an allocation fails.

	TDs for an unlinked URB are removed from the schedule as soon
	as the URB is unlinked, rather than waiting until the URB is
	given back.  This way there's no risk of the controller still
	executing a TD after the URB completes.

	The urb->error_count values are now reported correctly.
	Although since they aren't used in any drivers except for
	debug messages in the system log, probably nobody cares.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>