dax: super.c: fix kernel-doc bad line warning

Convert an empty line to " *" to avoid a kernel-doc warning:

drivers/dax/super.c:478: warning: bad line:

Signed-off-by: Randy Dunlap <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Vishal Verma <[email protected]>
Cc: Dave Jiang <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Dan Williams <[email protected]>

Author: rddunlap

drivers/dax/super.c

@@ -475,7 +475,7 @@ EXPORT_SYMBOL_GPL(put_dax);
 /**
  * dax_holder() - obtain the holder of a dax device
  * @dax_dev: a dax_device instance
-
+ *
  * Return: the holder's data which represents the holder if registered,
  * otherwize NULL.
  */