ide: remove ->dma_{status,command} fields from ide_hwif_t

* Use ->dma_base + offset instead of ->dma_{status,command}
  and remove no longer needed ->dma_{status,command}.

While at it:

* Use ATA_DMA_* defines.

There should be no functional changes caused by this patch.

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 fca89ed..1c2f9df 100644
--- a/drivers/ide/pci/pdc202xx_old.c
+++ b/drivers/ide/pci/pdc202xx_old.c
@@ -206,7 +206,7 @@
 {
 	ide_hwif_t *hwif	= HWIF(drive);
 	unsigned long high_16	= hwif->extra_base - 16;
-	u8 dma_stat		= inb(hwif->dma_status);
+	u8 dma_stat		= inb(hwif->dma_base + ATA_DMA_STATUS);
 	u8 sc1d			= inb(high_16 + 0x001d);
 
 	if (hwif->channel) {