MAINTAINERS: add myself as maintainer of AFFS

The AFFS filesystem is still in use by m68k community (Link #2), but as
there was no code activity and no maintainer, the filesystem appeared on
the list of candidates for staging/removal (Link #1).

I volunteer to act as a maintainer of AFFS to collect any fixes that
might show up and to guard fs/affs/ against another spring cleaning.

Link: https://lkml.kernel.org/r/20180425154602.GA8546@bombadil.infradead.org
Link: https://lkml.kernel.org/r/1613268.lKBQxPXt8J@merkaba
CC: Martin Steigerwald <martin@lichtvoll.de>
CC: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MAINTAINERS

@@ -564,8 +564,9 @@ S:	Maintained
 F:	drivers/media/dvb-frontends/af9033*
 
 AFFS FILE SYSTEM
+M:	David Sterba <dsterba@suse.com>
 L:	linux-fsdevel@vger.kernel.org
-S:	Orphan
+S:	Odd Fixes
 F:	Documentation/filesystems/affs.txt
 F:	fs/affs/