LU-11662 llite: handle -ENODATA in ll_layout_fetch()

LU-11662 llite: handle -ENODATA in ll_layout_fetch()

In ll_layout_fetch() handle -ENODATA returns from mdc_getxattr(). This
is needed for interop and restores the behavior from before commit
0f42b388432c4b898857660197ef13a40a82cd9d (LU-11380 mdc: move empty
xattr to mdc layer) landed.

Test-Parameters: clientjob=lustre-b2_10 clientbuildno=136 testlist=sanity-hsm
Test-Parameters: mdsjob=lustre-b2_10 ossjob=lustre-b2_10 serverbuildno=136 testlist=sanity-hsm
Signed-off-by: John L. Hammond <jhammond@whamcloud.com>
Change-Id: I1fb85faf35c7d2303a1f61a5a9c5922988739817
Reviewed-on: https://review.whamcloud.com/33665
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>