xen: xenbus: use put_device() instead of kfree()

BugLink: https://bugs.launchpad.net/bugs/1775771

[ Upstream commit 351b2bcc ]

Never directly free @dev after calling device_register(), even
if it returned an error! Always use put_device() to give up the
reference initialized.
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/xen/xenbus/xenbus_probe.c

@@ -470,8 +470,11 @@ int xenbus_probe_node(struct xen_bus_type *bus,
 
 	/* Register with generic device framework. */
 	err = device_register(&xendev->dev);
-	if (err)
+	if (err) {
+		put_device(&xendev->dev);
+		xendev = NULL;
 		goto fail;
+	}
 
 	return 0;
 fail: