fs/hfs/btree.h: remove duplicate defines

This patch removes duplicate defines from fs/hfs/btree.h

[akpm@linux-foundation.org: retain the comments]
Signed-off-by: Michael Opdenacker <michael.opdenacker@free-electrons.com>
Reviewed-by: Vyacheslav Dubeyko <slava@dubeyko.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>