f2fs: fix error path of fill_super

In fill_super, if root inode's attribute is incorrect, we need to
call f2fs_destroy_stats to release stats memory.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/super.c

@@ -2911,7 +2911,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 	if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
 		iput(root);
 		err = -EINVAL;
-		goto free_node_inode;
+		goto free_stats;
 	}
 
 	sb->s_root = d_make_root(root); /* allocate root dentry */