core: platform: add warning if driver has no owner

Commit 9447057e ("platform_device: use a macro instead of
platform_driver_register") introduced a codepath which could result into
drivers having no owner. This went unnoticed for months, so add a
warning in case this happens again somewhere else somewhen.
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/driver.c

@@ -151,6 +151,9 @@ int driver_register(struct device_driver *drv)
 
 	BUG_ON(!drv->bus->p);
 
+	if (!drv->owner)
+		printk(KERN_WARNING "Driver '%s' needs an owner", drv->name);
+
 	if ((drv->bus->probe && drv->probe) ||
 	    (drv->bus->remove && drv->remove) ||
 	    (drv->bus->shutdown && drv->shutdown))