xfs: remove the unnecessary xfs_dqid_t type cast

Since the type prid_t and xfs_dqid_t both are uint32_t, seems the
type cast is unnecessary, so remove it.

Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>