xfs: don't allow SWAPEXT if we'd screw up quota accounting

Since the old SWAPEXT ioctl doesn't know how to adjust quota ids,
bail out of the ids don't match and quotas are enabled.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>