USB: Fix a bug in usb_start_wait_urb

This patch (as941) fixes a bug recently added to the USB synchronous
API.  The status of a completed URB must be preserved separately
across a completion callback.  Also, the actual_length value isn't
available until after the URB has fully completed.

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