LU-16796 lov: Change struct lov_stripe_md to use kref

LU-16796 lov: Change struct lov_stripe_md to use kref

This patch changes struct lov_stripe_md to use
kref instead of atomic_t

Signed-off-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Change-Id: I8c743d630c268a70ecd0d5c9907e2ce456cd60cc
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56104
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Timothy Day <timday@amazon.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Oleg Drokin <green@whamcloud.com>