LU-2449 osd: lookup(..) to fetch fid from parent's LMA

LU-2449 osd: lookup(..) to fetch fid from parent's LMA

in case LinkEA is not accessible for a reason, osd-zfs
will be trying to get fid for ".." using parent's dnode
which is stored in regular ZFS attributes. parent's
LMA can be used to get fid for ".."

Signed-off-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Change-Id: I34e9f884eb60f036c2f941013bf22e154efc2ff4
Reviewed-on: http://review.whamcloud.com/5629
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>