LU-14951 llite: protect fd_{lease_}och

LU-14951 llite: protect fd_{lease_}och

Access ll_file_data::fd_och and fd_lease_och needs to lli_och_mutex
protection.

Signed-off-by: Bobi Jam <bobijam@whamcloud.com>
Change-Id: Ie9136aa345c6bf015aa73067acdaecf1a765b9f6
Reviewed-on: https://review.whamcloud.com/44700
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Yingjin Qian <qian@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>