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/pdc202xx_old.c b/drivers/ide/pci/pdc202xx_old.c
index 22c7a75..67b2781 100644
--- a/drivers/ide/pci/pdc202xx_old.c
+++ b/drivers/ide/pci/pdc202xx_old.c
@@ -375,6 +375,11 @@
 	}
 }
 
+#define IDE_HFLAGS_PDC202XX \
+	(IDE_HFLAG_ERROR_STOPS_FIFO | \
+	 IDE_HFLAG_ABUSE_SET_DMA_MODE | \
+	 IDE_HFLAG_OFF_BOARD)
+
 #define DECLARE_PDC2026X_DEV(name_str, udma, extra_flags) \
 	{ \
 		.name		= name_str, \
@@ -382,9 +387,7 @@
 		.init_hwif	= init_hwif_pdc202xx, \
 		.init_dma	= init_dma_pdc202xx, \
 		.extra		= 48, \
-		.host_flags	= IDE_HFLAG_ERROR_STOPS_FIFO | \
-				  extra_flags | \
-				  IDE_HFLAG_OFF_BOARD, \
+		.host_flags	= IDE_HFLAGS_PDC202XX | extra_flags, \
 		.pio_mask	= ATA_PIO4, \
 		.mwdma_mask	= ATA_MWDMA2, \
 		.udma_mask	= udma, \
@@ -397,8 +400,7 @@
 		.init_hwif	= init_hwif_pdc202xx,
 		.init_dma	= init_dma_pdc202xx,
 		.extra		= 16,
-		.host_flags	= IDE_HFLAG_ERROR_STOPS_FIFO |
-				  IDE_HFLAG_OFF_BOARD,
+		.host_flags	= IDE_HFLAGS_PDC202XX,
 		.pio_mask	= ATA_PIO4,
 		.mwdma_mask	= ATA_MWDMA2,
 		.udma_mask	= ATA_UDMA2,