LU-5070 osd-zfs: get object's FID from its LMA EA

LU-5070 osd-zfs: get object's FID from its LMA EA

Do not assume that the FID-in-dirent is always valid. If the
FID-in-dirent is absent or invalid, then the osd_dir_lookup
needs to find out the FID from the target object's LMA EA.

It is the similar logic as osd-ldiskfs does.

Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: If75ff4ed03bd75a3385666842e94838ece3f4344
Reviewed-on: http://review.whamcloud.com/18595
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>