LU-16796 obdclass: Change struct jobid_pid_map to use refcount_t

LU-16796 obdclass: Change struct jobid_pid_map to use refcount_t

This patch changes struct jobid_pid_map to use
refcount_t(kref) instead of atomic_t

Signed-off-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Change-Id: Ia3458d5605a8cff2bb65476495c321fa98cf01dc
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/51747
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Timothy Day <timday@amazon.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>