asix: Fix return value in AX88172A driver bind function

Return -ENOTSUPP if the initialization fails because the
device is configured for a mode that is not supported by the driver.

Signed-off-by: Christian Riesch <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/usb/ax88172a.c

···
 		break;
 	default:
 		netdev_err(dev->net, "Interface mode not supported by driver\n");
+		ret = -ENOTSUPP;
 		goto free;
 	}