LU-13246 osd: unlock os_lock if it was locked

LU-13246 osd: unlock os_lock if it was locked

do not use the global state (which can change concurrently) for that.

Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: Idbdc3639bca50006dac00112205e1fee9c9a0e30
Reviewed-on: https://review.whamcloud.com/37547
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>