ide: remove ->ide_dma_check (take 2)

* Add IDE_HFLAG_TRUST_BIOS_FOR_DMA host flag for host drivers that depend
  on BIOS for programming device/controller for DMA.  Set it in cy82c693,
  generic, ns87415, opti621 and trm290 host drivers.

* Add IDE_HFLAG_VDMA host flag for host drivers using VDMA.  Set it in cs5520
  host driver.

* Teach ide_tune_dma() about IDE_HFLAG_TRUST_BIOS_FOR_DMA flag.

* Add generic ide_dma_check() helper and remove all open coded ->ide_dma_check
  implementations.  Fix all places checking for presence of ->ide_dma_check
  hook to check for ->ide_dma_on instead.

* Remove no longer needed code from config_drive_for_dma().

* Make ide_tune_dma() static.

v2:
* Fix config_drive_for_dma() return values.

* Fix ide-dma.c build for CONFIG_BLK_DEV_IDEDMA_PCI=n by adding
  dummy config_drive_for_dma() inline.

* Fix IDE_HFLAG_TRUST_BIOS_FOR_DMA handling in ide_dma_check().

* Fix init_hwif_it8213() comment.

There should be no functionality changes caused by this patch.

Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-io.c

@@ -219,11 +219,11 @@ static ide_startstop_t ide_start_power_step(ide_drive_t *drive, struct request *
 
 	case ide_pm_restore_dma:	/* Resume step 3 (restore DMA) */
 		/*
-		 * Right now, all we do is call hwif->ide_dma_check(drive),
+		 * Right now, all we do is call ide_set_dma(drive),
 		 * we could be smarter and check for current xfer_speed
 		 * in struct drive etc...
 		 */
-		if (drive->hwif->ide_dma_check == NULL)
+		if (drive->hwif->ide_dma_on == NULL)
 			break;
 		drive->hwif->dma_off_quietly(drive);
 		/*