f2fs: fix to show ino management cache size correctly

It needs to stat size of ino management cache with all type instead of
orphan ino type.

Fixes: 652be551 ("f2fs: show # of orphan inodes")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>