MAINTAINERS: add util-linux-ng package

(akpm: we often deal with util-linux and I (at least) can never remember
where they hang out).

Signed-off-by: Karel Zak <kzak@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>