ide: call ide_build_sglist() prior to ->dma_setup (v2)

* Re-map sg table if needed in ide_build_sglist().

* Move ide_build_sglist() call from ->dma_setup to its users.

* Un-export ide_build_sglist().

v2:
* Build fix for CONFIG_BLK_DEV_IDEDMA=n (noticed by Randy Dunlap).

There should be no functional changes caused by this patch.

Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-taskfile.c

@@ -103,6 +103,7 @@ ide_startstop_t do_rw_taskfile (ide_drive_t *drive, ide_task_t *task)
 		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))
 			return ide_stopped;
 		dma_ops->dma_exec_cmd(drive, tf->command);