xfs: remove XFS_IS_OQUOTA_ON macros

Remove the XFS_IS_OQUOTA_ON macros as it is obsoleted.

Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>