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/pci/cs5520.c b/drivers/ide/pci/cs5520.c
index fbce900..74c3e60 100644
--- a/drivers/ide/pci/cs5520.c
+++ b/drivers/ide/pci/cs5520.c
@@ -105,15 +105,6 @@
 	cs5520_set_pio_mode(drive, 0);
 }
 
-static int cs5520_config_drive_xfer_rate(ide_drive_t *drive)
-{
-	/* Tune the drive for PIO modes up to PIO 4 */	
-	ide_set_max_pio(drive);
-
-	/* Then tell the core to use DMA operations */
-	return 0;
-}
-
 /*
  *	We provide a callback for our nonstandard DMA location
  */
@@ -148,7 +139,6 @@
 		return;
 	}
 
-	hwif->ide_dma_check = &cs5520_config_drive_xfer_rate;
 	hwif->ide_dma_on = &cs5520_dma_on;
 
 	/* ATAPI is harder so leave it for now */
@@ -171,7 +161,8 @@
 		.init_hwif	= init_hwif_cs5520,		\
 		.autodma	= AUTODMA,			\
 		.bootable	= ON_BOARD,			\
-		.host_flags	= IDE_HFLAG_ISA_PORTS,		\
+		.host_flags	= IDE_HFLAG_ISA_PORTS |		\
+				  IDE_HFLAG_VDMA,		\
 		.pio_mask	= ATA_PIO4,			\
 	}