drop linux/ufs_fs.h from userspace export and relocate it to fs/ufs/ufs_fs.h

Per previous discussions about cleaning up ufs_fs.h, people just want
this straight up dropped from userspace export.  The only remaining
consumer (silo) has been fixed a while ago to not rely on this header.
This allows use to move it completely from include/linux/ to fs/ufs/
seeing as how the only in-kernel consumer is fs/ufs/.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: Jan Kara <jack@ucw.cz>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>