ide: add ->read_sff_dma_status method

Add ->read_sff_dma_status method for reading DMA Status register
and use it instead of ->INB.

While at it:

* Use inb() directly in ns87415.c::ns87415_dma_end().

There should be no functional changes caused by this patch.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide-iops.c b/drivers/ide/ide-iops.c
index 44aaec2..a09bf43 100644
--- a/drivers/ide/ide-iops.c
+++ b/drivers/ide/ide-iops.c
@@ -103,6 +103,14 @@
 		port_ops->maskproc(drive, mask);
 }
 
+static u8 ide_read_sff_dma_status(ide_hwif_t *hwif)
+{
+	if (hwif->host_flags & IDE_HFLAG_MMIO)
+		return readb((void __iomem *)hwif->dma_status);
+	else
+		return inb(hwif->dma_status);
+}
+
 static void ide_tf_load(ide_drive_t *drive, ide_task_t *task)
 {
 	ide_hwif_t *hwif = drive->hwif;
@@ -323,6 +331,8 @@
 
 void default_hwif_transport(ide_hwif_t *hwif)
 {
+	hwif->read_sff_dma_status = ide_read_sff_dma_status;
+
 	hwif->tf_load	  = ide_tf_load;
 	hwif->tf_read	  = ide_tf_read;