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/cs5535.c b/drivers/ide/pci/cs5535.c
index ddcbeba..50b3d77 100644
--- a/drivers/ide/pci/cs5535.c
+++ b/drivers/ide/pci/cs5535.c
@@ -190,7 +190,7 @@
 	.name		= "CS5535",
 	.init_hwif	= init_hwif_cs5535,
 	.host_flags	= IDE_HFLAG_SINGLE | IDE_HFLAG_POST_SET_MODE |
-			  IDE_HFLAG_BOOTABLE,
+			  IDE_HFLAG_ABUSE_SET_DMA_MODE | IDE_HFLAG_BOOTABLE,
 	.pio_mask	= ATA_PIO4,
 	.mwdma_mask	= ATA_MWDMA2,
 	.udma_mask	= ATA_UDMA4,