xfs: remove XFS_QM_LOCK/XFS_QM_UNLOCK/XFS_QM_HOLD/XFS_QM_RELE

Remove these macros which only obsfucated the code in rather nast ways.

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