CVE-2026-53029 fs/ntfs3: prevent uninitialized lcn caused by zero len

In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: prevent uninitialized lcn caused by zero len syzbot reported a uninit-value in ntfsiomapbegin 1. Since runs was not touched yet, runlookupentry immediately fails and returns false, which makes the value of "len" 0...