LU-4315 doc: updating lctl-[b-d] man page style

LU-4315 doc: updating lctl-[b-d] man page style

Updating files to match the new code style for Lustre manual pages as
enforced by 'contrib/scripts/checkpatch-man.pl'. This also includes
other changes like removing < > or { } for singular required
arguments and placing [ ] around optional ones as well as making all
arguments CAPITAL and italicized, literal arguments are bolded.

Only using features that appear in groff 1.22.3 as this is the
available version is CentOS 8.

Checked files:
- lctl-barrier.8
- lctl-changelog_deregister.8
- lctl-changelog_register.8
- lctl-clear_conf.8
- lctl-del_ost.8
- lctl-device_list.8
- lctl-dl.8

Test-Parameters: trivial
Signed-off-by: Frederick Dilger <fdilger@whamcloud.com>
Change-Id: Id214e36300b1b0806e7566cf71d3f97d778f8b79
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56027
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>