LU-15357 mdd: fix changelog context leak

LU-15357 mdd: fix changelog context leak

The mdd_changelog_clear() shouldn't skip llog_ctxt_put()
in case of error.

Fixes: 6b183927e1 (LU-14553 changelog: eliminate mdd_changelog_clear warning)
Signed-off-by: Mikhail Pershin <mpershin@whamcloud.com>
Change-Id: I9c9aa3ce0d11e8f67470b450d007f2a1081644c6
Reviewed-on: https://review.whamcloud.com/45831
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Olaf Faaland-LLNL <faaland1@llnl.gov>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>