The KUnit maintainers would like to maintain these files on their
side too (thanks!), so add them to their entry.

With this in place, `scripts/get_maintainer.pl` prints both sets
of maintainers/reviewers (i.e. KUnit and Rust) for those files,
which is the behavior we are looking for.
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>