f2fs: remove the unused ctor argument of f2fs_kmem_cache_create()

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index fbb41ba..199c964 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1878,7 +1878,7 @@
 int __init create_segment_manager_caches(void)
 {
 	discard_entry_slab = f2fs_kmem_cache_create("discard_entry",
-			sizeof(struct discard_entry), NULL);
+			sizeof(struct discard_entry));
 	if (!discard_entry_slab)
 		return -ENOMEM;
 	return 0;