USB: unusual_devs entry for Nokia 3250

Here is another unusual_devs entry (as760) for another Nokia device,
this time the 3250.

From: Mario Rettig <mariorettig@web.de>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Phil Dibowitz <phil@ipom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>