HSI: core: Fix return freed object in hsi_new_client

cl is freed on error of calling device_register, but this
object is return later, which will cause uaf issue. Fix it
by return NULL on error.

Signed-off-by: Chengfeng Ye <cyeaa@connect.ust.hk>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/hsi/hsi_core.c

@@ -102,6 +102,7 @@ struct hsi_client *hsi_new_client(struct hsi_port *port,
 	if (device_register(&cl->device) < 0) {
 		pr_err("hsi: failed to register client: %s\n", info->name);
 		put_device(&cl->device);
+		goto err;
 	}
 
 	return cl;