USB: serial: clean up usb-serial bus device removal

Make sure to unregister the tty-device before calling subdriver
port_remove.

This way remove will reverse probe, and specifically any port data
released in port_remove will be available throughout tty unregister.

Note that the order currently does not matter as the tty-layer can make
callbacks also after the device has been unregistered. This is
handled in usb-serial core using the disconnected flag, which is
already set when usb-serial bus device remove is called.

Cc: Peter Hurley <peter@hurleysoftware.com>
Reported-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/bus.c

@@ -106,14 +106,15 @@ static int usb_serial_device_remove(struct device *dev)
 	/* make sure suspend/resume doesn't race against port_remove */
 	usb_autopm_get_interface(port->serial->interface);
 
+	minor = port->number;
+	tty_unregister_device(usb_serial_tty_driver, minor);
+
 	device_remove_file(&port->dev, &dev_attr_port_number);
 
 	driver = port->serial->type;
 	if (driver->port_remove)
 		retval = driver->port_remove(port);
 
-	minor = port->number;
-	tty_unregister_device(usb_serial_tty_driver, minor);
 	dev_info(dev, "%s converter now disconnected from ttyUSB%d\n",
 		 driver->description, minor);