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>
diff --git a/drivers/ide/ide-iops.c b/drivers/ide/ide-iops.c
index aa73883..d4d790f 100644
--- a/drivers/ide/ide-iops.c
+++ b/drivers/ide/ide-iops.c
@@ -776,7 +776,7 @@
 //		msleep(50);
 
 #ifdef CONFIG_BLK_DEV_IDEDMA
-	if (hwif->ide_dma_check)	 /* check if host supports DMA */
+	if (hwif->ide_dma_on)	/* check if host supports DMA */
 		hwif->dma_host_off(drive);
 #endif
 
@@ -830,7 +830,7 @@
 #ifdef CONFIG_BLK_DEV_IDEDMA
 	if (speed >= XFER_SW_DMA_0)
 		hwif->dma_host_on(drive);
-	else if (hwif->ide_dma_check)	/* check if host supports DMA */
+	else if (hwif->ide_dma_on)	/* check if host supports DMA */
 		hwif->dma_off_quietly(drive);
 #endif