Since r233109, kldload has the -n option, which silently ignores options
that are already loaded.
https://lists.freebsd.org/pipermail/freebsd-rc/2018-December/003899.html
Note that this script no longer reports if the module is already loaded,
but it could be argued this wasn't particularly useful information.
PR: docs/234248
Reviewed by: bcr (docs), kib, rgrimes (visual)
Approved by: jilles
Differential Revision: https://reviews.freebsd.org/D18670
f5dfe75da5