ide: add ide_tune_dma() helper

After reworking the code responsible for selecting the best DMA
transfer mode it is now possible to add generic ide_tune_dma() helper.

Convert some IDE PCI host drivers to use it (the ones left need more work).

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/pci/jmicron.c

@@ -118,25 +118,6 @@ static int jmicron_tune_chipset (ide_drive_t *drive, byte xferspeed)
 	return ide_config_drive_speed(drive, speed);
 }
 
-/**
- *	config_chipset_for_dma	-	configure for DMA
- *	@drive: drive to configure
- *
- *	As the JMicron snoops for timings all we actually need to do is
- *	make sure we don't set an invalid mode.
- */
-
-static int config_chipset_for_dma (ide_drive_t *drive)
-{
-	u8 speed = ide_max_dma_mode(drive);
-
-	if (!speed)
-		return 0;
-
-	jmicron_tune_chipset(drive, speed);
-	return ide_dma_enable(drive);
-}
-
 /**
  *	jmicron_configure_drive_for_dma	-	set up for DMA transfers
  *	@drive: drive we are going to set up
@@ -147,7 +128,7 @@ static int config_chipset_for_dma (ide_drive_t *drive)
 
 static int jmicron_config_drive_for_dma (ide_drive_t *drive)
 {
-	if (ide_use_dma(drive) && config_chipset_for_dma(drive))
+	if (ide_tune_dma(drive))
 		return 0;
 
 	config_jmicron_chipset_for_pio(drive, 1);