LU-10100 llite: swab LOV EA user data

LU-10100 llite: swab LOV EA user data

Many sub-tests failed with "Invalid argument" failures
on PPC client because of the endianness issue.

This patch fixes the issue by adding a common function
lustre_swab_lov_user_md() to swab the LOV EA user data.

Test-Parameters: clientarch=ppc64 \
envdefinitions=ONLY=27 testlist=sanity

This patch is back-ported from the following one:
Lustre-commit: 9d17996766e0fa93b1029d2422d45d087edde389
Lustre-change: https://review.whamcloud.com/35291

Change-Id: I46bab0788300cd79c4e66e1a4990c3e1f7192391
Signed-off-by: Jian Yu <yujian@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/35633
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>