libata: Support chips with 64K PRD quirk

Add ata_dumb_qc_prep and supporting logic so that a driver can just
specify it needs to be helped in this area. 64K entries are split
as with drivers/ide.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/pata_cs5530.c b/drivers/ata/pata_cs5530.c
index 797a6f6..3fca589 100644
--- a/drivers/ata/pata_cs5530.c
+++ b/drivers/ata/pata_cs5530.c
@@ -167,7 +167,7 @@
 	.queuecommand		= ata_scsi_queuecmd,
 	.can_queue		= ATA_DEF_QUEUE,
 	.this_id		= ATA_SHT_THIS_ID,
-	.sg_tablesize		= LIBATA_MAX_PRD,
+	.sg_tablesize		= LIBATA_DUMB_MAX_PRD,
 	.cmd_per_lun		= ATA_SHT_CMD_PER_LUN,
 	.emulated		= ATA_SHT_EMULATED,
 	.use_clustering		= ATA_SHT_USE_CLUSTERING,
@@ -201,7 +201,7 @@
 	.post_internal_cmd = ata_bmdma_post_internal_cmd,
 	.cable_detect	= ata_cable_40wire,
 
-	.qc_prep 	= ata_qc_prep,
+	.qc_prep 	= ata_dumb_qc_prep,
 	.qc_issue	= cs5530_qc_issue_prot,
 
 	.data_xfer	= ata_data_xfer,