staging: gasket: Replace macro __ATTR with __ATTR_NULL

Replace macro __ATTR with __ATTR_NULL since the former one is
unnecessary for gasket_sysfs_attr array terminator. Also silence the
checkpatch.pl warning:
WARNING:Symbolic permissions 'S_IRUGO' are not preferred. Consider using
octal
permissions '0444'.
Signed-off-by: Wentao Cai <etsai042@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gasket/gasket_sysfs.h

@@ -40,7 +40,7 @@
  */
 #define GASKET_END_OF_ATTR_ARRAY                                               \
 	{                                                                      \
-		.attr = __ATTR(GASKET_ARRAY_END_TOKEN, S_IRUGO, NULL, NULL),   \
+		.attr = __ATTR_NULL,				\
 		.data.attr_type = 0,				\
 	}