USB: keyspan: fix bogus array index

commit a0708809 upstream.

The outcont_endpoints array was indexed using the port minor number
(which can be greater than the array size) rather than the device port
number.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/usb/serial/keyspan.c

@@ -1833,7 +1833,7 @@ static int keyspan_usa26_send_setup(struct usb_serial *serial,
 	d_details = s_priv->device_details;
 	device_port = port->number - port->serial->minor;
 
-	outcont_urb = d_details->outcont_endpoints[port->number];
+	outcont_urb = d_details->outcont_endpoints[device_port];
 	this_urb = p_priv->outcont_urb;
 
 	dbg("%s - endpoint %d", __func__, usb_pipeendpoint(this_urb->pipe));