vfio/mdev: Use a module softdep for vfio_mdev

Use an explicit module softdep rather than a request module call such
that the dependency is exposed to userspace.  This allows us to more
easily support modules loaded at initrd time.

Reviewed by: Kirti Wankhede <kwankhede@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/mdev/mdev_core.c

@@ -422,18 +422,7 @@ int mdev_device_remove(struct device *dev, bool force_remove)
 
 static int __init mdev_init(void)
 {
-	int ret;
-
-	ret = mdev_bus_register();
-
-	/*
-	 * Attempt to load known vfio_mdev.  This gives us a working environment
-	 * without the user needing to explicitly load vfio_mdev driver.
-	 */
-	if (!ret)
-		request_module_nowait("vfio_mdev");
-
-	return ret;
+	return mdev_bus_register();
 }
 
 static void __exit mdev_exit(void)
@@ -451,3 +440,4 @@ MODULE_VERSION(DRIVER_VERSION);
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR(DRIVER_AUTHOR);
 MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_SOFTDEP("post: vfio_mdev");