LU-18641 mdt: remove trivial locking wrapper

LU-18641 mdt: remove trivial locking wrapper

These wrappers around mot_dom_sem haven't changed in 10
years. It's unlikely they will grow to be more than trivial
wrappers. Remove them.

Test-Parameters: trivial
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: I594741404cfc820552d917a54f10e89f331e3a71
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/57798
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Mikhail Pershin <mpershin@whamcloud.com>
Reviewed-by: Max Wang <wamax@amazon.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>