sata_sis has the same restrictions as other SFF controllers, and so must
use LIBATA_MAX_PRD to denote that SCSI may only fill ATA_MAX_PRD/2
entries, due to our need to handle IOMMU merging.
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
        .queuecommand           = ata_scsi_queuecmd,
        .can_queue              = ATA_DEF_QUEUE,
        .this_id                = ATA_SHT_THIS_ID,
-       .sg_tablesize           = ATA_MAX_PRD,
+       .sg_tablesize           = LIBATA_MAX_PRD,
        .cmd_per_lun            = ATA_SHT_CMD_PER_LUN,
        .emulated               = ATA_SHT_EMULATED,
        .use_clustering         = ATA_SHT_USE_CLUSTERING,