LU-6471 obdclass: fix llog_cat_cleanup() usage on Client

LU-6471 obdclass: fix llog_cat_cleanup() usage on Client

With patch/commit 3a83b4b9 for LU-5195, LLOG code has been
strengthen against catalog inconsistency by detecting a
referenced plain LLOG is missing and by clearing its
associated entry by calling llog_cat_cleanup(), which now
needs to handle the case where it is also executed on a Client
(ie, cathandle->lgh_obj == NULL) and thus must not attempt to
update on-disk catalog.

Signed-off-by: Bruno Faccini <bruno.faccini@intel.com>
Change-Id: Ie6fb9240ac76810358a91c7410046c626f42c2b9
Reviewed-on: http://review.whamcloud.com/14489
Tested-by: Jenkins
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>