USB: serial: kl5kusb105: fix line-state error handling

The current implementation failed to detect short transfers when
attempting to read the line state, and also, to make things worse,
logged the content of the uninitialised heap transfer buffer.

Fixes: abf492e7b3ae ("USB: kl5kusb105: fix DMA buffers on stack")
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
static int klsi_105_tiocmget(struct tty_struct *tty)
{
	struct usb_serial_port *port = tty->driver_data;
	struct klsi_105_private *priv = usb_get_serial_port_data(port);
	unsigned long flags;
	int rc;
	unsigned long line_state;

	rc = klsi_105_get_line_state(port, &line_state);
	if (rc < 0) {
		dev_err(&port->dev,
			"Reading line control failed (error = %d)\n", rc);
		/* better return value? EAGAIN? */
		return rc;
	}

	spin_lock_irqsave(&priv->lock, flags);
	priv->line_state = line_state;
	spin_unlock_irqrestore(&priv->lock, flags);
	dev_dbg(&port->dev, "%s - read line state 0x%lx\n", __func__, line_state);
	return (int)line_state;
}

static int klsi_105_tiocmget(struct tty_struct *tty)
{
	struct usb_serial_port *port = tty->driver_data;
	struct klsi_105_private *priv = usb_get_serial_port_data(port);
	unsigned long flags;
	int rc;
	unsigned long line_state;

	rc = klsi_105_get_line_state(port, &line_state);
	if (rc < 0) {
		dev_err(&port->dev,
			"Reading line control failed (error = %d)\n", rc);
		/* better return value? EAGAIN? */
		return rc;
	}

	spin_lock_irqsave(&priv->lock, flags);
	priv->line_state = line_state;
	spin_unlock_irqrestore(&priv->lock, flags);
	dev_dbg(&port->dev, "%s - read line state 0x%lx\n", __func__, line_state);
	return (int)line_state;
}
