USB: remove Iso status value in uhci-hcd

This patch (968) changes the way uhci-hcd reports status for
Isochronous URBs.  Until now urb->status has been set to the last
detected error code.  But other HCDs don't do this; they leave the
status set to 0 and report errors only in the individual iso packet
descriptors.  So this patch removes the extra computation and makes
uhci-hcd behave like the others.

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