ext3: dirindex error pointer issues

- ext3_dx_find_entry() exit with out setting proper error pointer

- do_split() exit with out setting proper error pointer
  it is realy painful because many callers contain folowing code:

          de = do_split(handle,dir, &bh, frame, &hinfo, &retval);
          if (!(de))
                       return retval;
          <<< WOW retval wasn't changed by do_split(), so caller failed
          <<< but return SUCCESS :)

- Rearrange do_split() error path. Current error path is realy ugly, all
  this up and down jump stuff doesn't make code easy to understand.

[dmonakhov@sw.ru: fix annoying fake error messages]
Signed-off-by: Monakhov Dmitriy <dmonakhov@openvz.org>
Cc: Andreas Dilger <adilger@clusterfs.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Monakhov Dmitriy <dmonakhov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>