LU-16082 ldiskfs: old-style EA inode handling fix

LU-16082 ldiskfs: old-style EA inode handling fix

The upstream version of EA inodes support coming
with RHEL8 (linux kernel 4.18+) have a slightly different
implementation of EA inodes support and also have a
compatibility code to recognize old-style Lustre-only EAs.
Unfortunately the compatibility code is broken and makes
old xattr data unaccessible due to a wrong hash value check.

HPE-bug-id: LUS-11133
Signed-off-by: Alexander Zarochentsev <alexander.zarochentsev@hpe.com>
Change-Id: Icd6f93d4ebb33dcd03b58f9eb364905c18ae81dc
Reviewed-on: https://review.whamcloud.com/48174
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Artem Blagodarenko <ablagodarenko@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>