LU-6142 lov: simplfy lov_finish_set()

LU-6142 lov: simplfy lov_finish_set()

When deleting everything from a list, a while loop
is cleaner than list_for_each_safe().

Linux-commit: dff162689a4061ff30d3a05f9d790e375c06ab8f

Change-Id: I90d98ebf14f461796d6f9d31a2c62de1520034cc
Signed-off-by: Mr. NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/49735
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>