xfs: format logged extents directly into the CIL

With the new iop_format scheme there is no need to have a temporary buffer
to format logged extents into, we can do so directly into the CIL.  This
also allows to remove the shortcut for big endian systems that probably
hasn't gotten a lot of test coverage for a long time.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>