xfs: stop using q_core limits in the quota code

xfs: stop using q_core limits in the quota code

Add limits fields in the incore dquot, and use that instead of the ones
in qcore.  This eliminates a bunch of endian conversions and will
eventually allow us to remove qcore entirely.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Allison Collins <allison.henderson@oracle.com>