autofs: set ctime as well when mtime changes on a dir

When adding entries to a directory, POSIX generally requires that the
ctime also be updated alongside the mtime.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Ian Kent <raven@themaw.net>
Message-Id: <20230612104524.17058-4-jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>