LU-5871 lod: Do not return EAGAIN in lod_object_init

Convert EAGAIN to EIO if fld_client_rpc() fails in
lod_object_init(), otherwise it will confuse
lu_object_find_at(), and make it wait there for no
reason, which should only wait if the object is dying.
See call chain lu_object_find_at()-> lu_object_find_try()
->lu_object_alloc()->lod_object_init()->lod_fld_lookup()
->fld_client_rpc(), and even worse waitq is not being
initialized yet when the failure happened here.

Change-Id: Ieae434b34c239efea86a4a471fb01e397336a31c
Signed-off-by: Wang Di <di.wang@intel.com>
Reviewed-on: http://review.whamcloud.com/12586
Tested-by: Jenkins
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>