qeth: replace PTR_RET with PTR_ERR_OR_ZERO

PTR_RET is deprecated. Do not recommend its usage anymore.
Use PTR_ERR_OR_ZERO instead.

Signed-off-by: Duan Jiong <duanj.fnst@cn.fujitsu.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/s390/net/qeth_core_main.c

@@ -5824,7 +5824,7 @@ static int __init qeth_core_init(void)
 	if (rc)
 		goto out_err;
 	qeth_core_root_dev = root_device_register("qeth");
-	rc = PTR_RET(qeth_core_root_dev);
+	rc = PTR_ERR_OR_ZERO(qeth_core_root_dev);
 	if (rc)
 		goto register_err;
 	qeth_core_header_cache = kmem_cache_create("qeth_hdr",