CVE-2022-50743 erofs: Fix pcluster memleak when its block address is zero

In the Linux kernel, the following vulnerability has been resolved: erofs: Fix pcluster memleak when its block address is zero syzkaller reported a memleak: https://syzkaller.appspot.com/bug?id=62f37ff612f0021641eda5b17f056f1668aa9aed unreferenced object 0xffff88811009c7f8 size 136: ... backtrace...