docbook: fix drivers/base/class warning

Fix kernel-doc empty line warning:
Warning(linux-2.6.24-git8//drivers/base/class.c:866): bad line:
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/base/class.c

@@ -863,7 +863,7 @@ EXPORT_SYMBOL_GPL(class_for_each_device);
  * The callback should return 0 if the device doesn't match and non-zero
  * if it does.  If the callback returns non-zero, this function will
  * return to the caller and not iterate over any more devices.
-
+ *
  * Note, you will need to drop the reference with put_device() after use.
  *
  * We hold class->sem in this function, so it can not be