This patch removes an unneeded "status" field from the UHCI driver's
URB-private data structure.  The driver had been storing the status of
completed URBs there rather than in the URBs themselves.  This not only is
wasteful of space but is also a cause of bugs, since the USB core relies
on urb->status for proper synchronization with the driver.

The patch also takes care of a number of small things that have been
bugging me for ages:

	Close a small loophole by allowing an URB to be unlinked even
	before the uhci_urb_enqueue() procedure has started.

	Remove some fossil code from back when interrupt URBs were
	automagically resubmitted.

	Giveback unlinked URBs in the order they were unlinked.

	Don't set urb->status for dequeued URBs; the core has already
	set it for us.

	Rename uhci_remove_pending_qhs to uhci_remove_pending_urbps.
	(That has _really_ bothered me!)