serial: etraxfs-uart: Fix release etraxfs_uart_ports

In probe, we use dev_id as array index of etraxfs_uart_ports and store the
index in port->line. So etraxfs_uart_ports[port->line] should be released
when unload the module.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Niklas Cassel <nks@flawful.org>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/etraxfs-uart.c

@@ -950,7 +950,7 @@ static int etraxfs_uart_remove(struct platform_device *pdev)
 
 	port = platform_get_drvdata(pdev);
 	uart_remove_one_port(&etraxfs_uart_driver, port);
-	etraxfs_uart_ports[pdev->id] = NULL;
+	etraxfs_uart_ports[port->line] = NULL;
 
 	return 0;
 }