f2fs: adjust kernel coding style

As pointed out by Randy Dunlap, this patch removes all usage of "/**" for comment
blocks. Instead, just use "/*".

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
diff --git a/fs/f2fs/hash.c b/fs/f2fs/hash.c
index beb155e..a60f042 100644
--- a/fs/f2fs/hash.c
+++ b/fs/f2fs/hash.c
@@ -1,4 +1,4 @@
-/**
+/*
  * fs/f2fs/hash.c
  *
  * Copyright (c) 2012 Samsung Electronics Co., Ltd.