xfs: remove the quotaoff log format from the quotaoff log item

This one doesn't save a whole lot of memory, but still makes the
code simpler.

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