ide: pass command to ide_map_sg()

* Set IDE_TFLAG_WRITE flag and ->rq also for ATA_CMD_PACKET
  commands.

* Pass command to ->dma_setup method and update all its
  implementations accordingly.

* Pass command instead of request to ide_build_sglist(),
  *_build_dmatable() and ide_map_sg().

While at it:

* Fix scc_dma_setup() documentation + use ATA_DMA_WR define.

* Rename sgiioc4_build_dma_table() to sgiioc4_build_dmatable(),
  change return value type to 'int' and drop unused 'ddir'
  argument.

* Do some minor cleanups in [tx4939]ide_dma_setup().

There should be no functional changes caused by this patch.

Acked-by: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide-taskfile.c b/drivers/ide/ide-taskfile.c
index db6d782..3b23bd1 100644
--- a/drivers/ide/ide-taskfile.c
+++ b/drivers/ide/ide-taskfile.c
@@ -102,8 +102,8 @@
 		return ide_started;
 	default:
 		if ((drive->dev_flags & IDE_DFLAG_USING_DMA) == 0 ||
-		    ide_build_sglist(drive, hwif->rq) == 0 ||
-		    dma_ops->dma_setup(drive))
+		    ide_build_sglist(drive, cmd) == 0 ||
+		    dma_ops->dma_setup(drive, cmd))
 			return ide_stopped;
 		dma_ops->dma_exec_cmd(drive, tf->command);
 		dma_ops->dma_start(drive);