LU-10187 osd-zfs: repair FID-in-dirent for ZFS backend

LU-10187 osd-zfs: repair FID-in-dirent for ZFS backend

If the ZFS backend is restored from MDT file-level backup, then
the FID-in-dirent will be lost. The patch can regenerate/repair
the lost/corrupted FID-in-dirent during namespace LFSCK.

Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: I747cdb75adc93971a7450f9e6b5e99598c79f656
Reviewed-on: https://review.whamcloud.com/28609
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>