driver-core: fix missing kernel-doc in firmware_class

Fix kernel-doc warning in firmware_class.c:

Warning(drivers/base/firmware_class.c:94): No description found for parameter 'attr'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index fc7565c..18518ba 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -78,6 +78,7 @@
 /**
  * firmware_timeout_store - set number of seconds to wait for firmware
  * @class: device class pointer
+ * @attr: device attribute pointer
  * @buf: buffer to scan for timeout value
  * @count: number of bytes in @buf
  *