reiserfs: remove link detection code

Early in the reiserfs xattr development, there was a plan to use
hardlinks to save disk space for identical xattrs.  That code never
materialized and isn't going to, so this patch removes the detection
code.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>