xfs: rename bli_format to avoid confusion with bli_formats

Rename the bli_format structure to __bli_format to avoid
accidently confusing them with the bli_formats pointer.

Signed-off-by: Mark Tinguely <tinguely@sgi.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>