fsck.f2fs: check ino of an used nat entry
fsck.f2fs: check ino of an used nat entry

If a nid is valid, the ino in its nat entry should record its parent nid.
However if the ino is zero, we should drop the node.

Signed-off-by: Sheng Yong <ce77ec10379c6f281208b7b41f03fd701be51d81@huawei.com>
Signed-off-by: Xue Liu <7a8409a5ff413510d343df4552e688f657635449@huawei.com>
Signed-off-by: Jaegeuk Kim <71255387a32c360dfbe6dfb7aaeb123bf1dc8cb6@kernel.org>

PAC-ROM/android_external_f2fs-tools,PAC-ROM/android_external_f2fs-tools