erofs: fix incorrect early exits for invalid metabox-enabled images

erofs: fix incorrect early exits for invalid metabox-enabled images

Crafted EROFS images with metadata compression enabled can trigger
incorrect early returns, leading to folio reference leaks.

However, this does not cause system crashes or other severe issues.

Fixes: 414091322c63 ("erofs: implement metadata compression")
Cc: stable@kernel.org
Reviewed-by: Hongbo Li <lihongbo22@huawei.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>