MAINTAINERS: add an entry for the Macintosh HFSPlus Filesystem

To make scripts/get_maintainer.pl output something sensible.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>