usb/isp1760: Report correct urb status after unlink

This fixes a bug in my previous (2.6.38) patch series which caused
urb->status value to be wrong after unlink (broke usbtest 11, 12).

Signed-off-by: Arvid Brodin <arvid.brodin@enea.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>