libata-sff: clean up inheritance in several drivers

1. pata_cmd640 is PIO only.  Inherit from sff.

2. pata_macio is BMDMA.  Inherit from bmdma and drop explicit
   bmdma_mode_filter() setting.

3. In sata_mv, unlike mv5, mv6 is BMDMA.  Inherit from bmdma and
   don't clear ->post_internal_cmd().

4. bf54x and icside are quasi-BMDMA controllers which don't use the
   standard BMDMA registers so they don't initialize bmdma_addr and
   inherit from sff to avoid the default mode_filter which disables
   DMA modes if bmdma_addr is not initialized.

For 2 and 3, this patch makes the drivers explicitly specify
->mode_filter to ATA_OP_NULL while inheriting from ata_bmdma_port_ops.
These will be removed by the next patch.

This patch makes all and only BMDMA drivers inherit from
ata_bmdma_port_ops to ease further SFF/BMDMA separation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/pata_cmd640.c

@@ -166,11 +166,11 @@ static int cmd640_port_start(struct ata_port *ap)
 }
 
 static struct scsi_host_template cmd640_sht = {
-	ATA_BMDMA_SHT(DRV_NAME),
+	ATA_PIO_SHT(DRV_NAME),
 };
 
 static struct ata_port_operations cmd640_port_ops = {
-	.inherits	= &ata_bmdma_port_ops,
+	.inherits	= &ata_sff_port_ops,
 	/* In theory xfer_noirq is not needed once we kill the prefetcher */
 	.sff_data_xfer	= ata_sff_data_xfer_noirq,
 	.qc_issue	= cmd640_qc_issue,