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/siimage.c b/drivers/ide/pci/siimage.c
index 6e9d765..21d7137 100644
--- a/drivers/ide/pci/siimage.c
+++ b/drivers/ide/pci/siimage.c
@@ -334,7 +334,7 @@
 	unsigned long addr	= siimage_selreg(hwif, 1);
 
 	/* return 1 if INTR asserted */
-	if (hwif->INB(hwif->dma_status) & 4)
+	if (inb(hwif->dma_base + ATA_DMA_STATUS) & 4)
 		return 1;
 
 	/* return 1 if Device INTR asserted */
@@ -382,7 +382,7 @@
 	}
 
 	/* return 1 if INTR asserted */
-	if (readb((void __iomem *)hwif->dma_status) & 0x04)
+	if (readb((void __iomem *)(hwif->dma_base + ATA_DMA_STATUS)) & 4)
 		return 1;
 
 	/* return 1 if Device INTR asserted */