USB: serial: io_ti: bind to interface after fw download

Bind to the interface, but do not register any ports, after having
downloaded the firmware. The device will still disconnect and
re-enumerate, but this way we avoid an error messages from being logged
as part of the process:

io_ti: probe of 1-1.3:1.0 failed with error -5
Signed-off-by: Johan Hovold <johan@kernel.org>

drivers/usb/serial/io_ti.c

@@ -1499,8 +1499,7 @@ static int do_boot_mode(struct edgeport_serial *serial,
 
 		dev_dbg(dev, "%s - Download successful -- Device rebooting...\n", __func__);
 
-		/* return an error on purpose */
-		return -ENODEV;
+		return 1;
 	}
 
 stayinbootmode: