net: net_netdev: Fix error handling in ntb_netdev_init_module()

The ntb_netdev_init_module() returns the ntb_transport_register_client()
directly without checking its return value, if
ntb_transport_register_client() failed, the NTB client device is not
unregistered.

Fix by unregister NTB client device when ntb_transport_register_client()
failed.

Fixes: 548c237c0a99 ("net: Add support for NTB virtual ethernet device")
Signed-off-by: Yuan Can <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ntb_netdev.c

···
 	rc = ntb_transport_register_client_dev(KBUILD_MODNAME);
 	if (rc)
 		return rc;
-	return ntb_transport_register_client(&ntb_netdev_client);
+
+	rc = ntb_transport_register_client(&ntb_netdev_client);
+	if (rc) {
+		ntb_transport_unregister_client_dev(KBUILD_MODNAME);
+		return rc;
+	}
+
+	return 0;
 }
 module_init(ntb_netdev_init_module);