ide: add IDE_HFLAG_ABUSE_SET_DMA_MODE host flag

* Add IDE_HFLAG_ABUSE_SET_DMA_MODE host flag and use it to decide
  what to do with transfer modes < XFER_PIO_0 in ide_set_xfer_rate().

* Set IDE_HFLAG_ABUSE_SET_DMA_MODE in host drivers that need it
  (aec62xx, amd74xx, cs5520, cs5535, hpt34x, hpt366, pdc202xx_old,
  serverworks, tc86c001 and via82cxxx) and cleanup ->set_dma_mode
  methods in host drivers that don't (IDE core code guarantees that
  ->set_dma_mode will be called only for modes which are present
  in SWDMA/MWDMA/UDMA masks).

While at it:

* Add IDE_HFLAGS_HPT34X/HPT3XX/PDC202XX/SVWKS define in
  hpt34x/hpt366/pdc202xx_old/serverworks host driver.

There should be no functionality changes caused by this patch.

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/pci/aec62xx.c b/drivers/ide/pci/aec62xx.c
index 4426850..7f4d185 100644
--- a/drivers/ide/pci/aec62xx.c
+++ b/drivers/ide/pci/aec62xx.c
@@ -202,6 +202,7 @@
 		.enablebits	= {{0x4a,0x02,0x02}, {0x4a,0x04,0x04}},
 		.host_flags	= IDE_HFLAG_SERIALIZE |
 				  IDE_HFLAG_NO_ATAPI_DMA |
+				  IDE_HFLAG_ABUSE_SET_DMA_MODE |
 				  IDE_HFLAG_OFF_BOARD,
 		.pio_mask	= ATA_PIO4,
 		.mwdma_mask	= ATA_MWDMA2,
@@ -211,6 +212,7 @@
 		.init_chipset	= init_chipset_aec62xx,
 		.init_hwif	= init_hwif_aec62xx,
 		.host_flags	= IDE_HFLAG_NO_ATAPI_DMA | IDE_HFLAG_NO_AUTODMA |
+				  IDE_HFLAG_ABUSE_SET_DMA_MODE |
 				  IDE_HFLAG_OFF_BOARD,
 		.pio_mask	= ATA_PIO4,
 		.mwdma_mask	= ATA_MWDMA2,
@@ -220,7 +222,8 @@
 		.init_chipset	= init_chipset_aec62xx,
 		.init_hwif	= init_hwif_aec62xx,
 		.enablebits	= {{0x4a,0x02,0x02}, {0x4a,0x04,0x04}},
-		.host_flags	= IDE_HFLAG_NO_ATAPI_DMA,
+		.host_flags	= IDE_HFLAG_NO_ATAPI_DMA |
+				  IDE_HFLAG_ABUSE_SET_DMA_MODE,
 		.pio_mask	= ATA_PIO4,
 		.mwdma_mask	= ATA_MWDMA2,
 		.udma_mask	= ATA_UDMA4,
@@ -228,7 +231,9 @@
 		.name		= "AEC6280",
 		.init_chipset	= init_chipset_aec62xx,
 		.init_hwif	= init_hwif_aec62xx,
-		.host_flags	= IDE_HFLAG_NO_ATAPI_DMA | IDE_HFLAG_OFF_BOARD,
+		.host_flags	= IDE_HFLAG_NO_ATAPI_DMA |
+				  IDE_HFLAG_ABUSE_SET_DMA_MODE |
+				  IDE_HFLAG_OFF_BOARD,
 		.pio_mask	= ATA_PIO4,
 		.mwdma_mask	= ATA_MWDMA2,
 		.udma_mask	= ATA_UDMA5,
@@ -237,7 +242,9 @@
 		.init_chipset	= init_chipset_aec62xx,
 		.init_hwif	= init_hwif_aec62xx,
 		.enablebits	= {{0x4a,0x02,0x02}, {0x4a,0x04,0x04}},
-		.host_flags	= IDE_HFLAG_NO_ATAPI_DMA | IDE_HFLAG_OFF_BOARD,
+		.host_flags	= IDE_HFLAG_NO_ATAPI_DMA |
+				  IDE_HFLAG_ABUSE_SET_DMA_MODE |
+				  IDE_HFLAG_OFF_BOARD,
 		.pio_mask	= ATA_PIO4,
 		.mwdma_mask	= ATA_MWDMA2,
 		.udma_mask	= ATA_UDMA5,