USB: reorganize urb->status use in usbmon

This patch (as978) reorganizes the way usbmon uses urb->status.  It
now accepts the status value as an argument.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>