fsck.f2fs: count child directories correctly for i_links
fsck.f2fs: count child directories correctly for i_links

If some of children including directories are corrupted, we should not include
them into i_links of their parent.
This patch fixes that.

Signed-off-by: Jaegeuk Kim <71255387a32c360dfbe6dfb7aaeb123bf1dc8cb6@kernel.org>

VanirAOSP/external_f2fs-tools,Euphoria-OS-Legacy/android_external_f2fs-tools,VanirAOSP/external_f2fs-tools,Euphoria-OS-Legacy/android_external_f2fs-tools,Fusion-Rom/android_external_f2fs-tools,Fusion-Rom/android_external_f2fs-tools