staging: fieldbus: anybus: Refuse registering drivers without .probe()

A driver without .probe() callback could never bind to a device because
anybus_bus_probe() returned an error for such a driver. So refuse to
register such a useless driver.

Reviewed-by: Sven Van Asbroeck <TheSven73@gmail.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20210505202923.198607-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fieldbus/anybuss/host.c

@@ -1183,8 +1183,6 @@ static int anybus_bus_probe(struct device *dev)
 	struct anybuss_client *adev =
 		to_anybuss_client(dev);
 
-	if (!adrv->probe)
-		return -ENODEV;
 	return adrv->probe(adev);
 }
 
@@ -1208,6 +1206,9 @@ static struct bus_type anybus_bus = {
 
 int anybuss_client_driver_register(struct anybuss_client_driver *drv)
 {
+	if (!drv->probe)
+		return -ENODEV;
+
 	drv->driver.bus = &anybus_bus;
 	return driver_register(&drv->driver);
 }