scsi: remove the use_clustering flag

The same effects can be achieved by setting the dma_boundary to
PAGE_SIZE - 1 and the max_segment_size to PAGE_SIZE, so shift those
settings into the drivers.  Note that in many cases the setting might
be bogus, but this keeps the status quo.

[mkp: fix myrs and myrb]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/myrb.c

@@ -2236,7 +2236,7 @@ struct scsi_host_template myrb_template = {
 	.shost_attrs		= myrb_shost_attrs,
 	.sdev_attrs		= myrb_sdev_attrs,
 	.this_id		= -1,
-	.use_clustering		= DISABLE_CLUSTERING,
+	.dma_boundary           = PAGE_SIZE - 1,
 };
 
 /**