ide: move command related fields from ide_hwif_t to struct ide_cmd

* Move command related fields from ide_hwif_t to struct ide_cmd.

* Make ide_init_sg_cmd() take command and sectors number as arguments.

There should be no functional changes caused by this patch.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/icside.c b/drivers/ide/icside.c
index 78fc36f..bdfeb12 100644
--- a/drivers/ide/icside.c
+++ b/drivers/ide/icside.c
@@ -344,7 +344,7 @@
 	 * Tell the DMA engine about the SG table and
 	 * data direction.
 	 */
-	set_dma_sg(ec->dma, hwif->sg_table, hwif->sg_nents);
+	set_dma_sg(ec->dma, hwif->sg_table, hwif->cmd.sg_nents);
 	set_dma_mode(ec->dma, dma_mode);
 
 	drive->waiting_for_dma = 1;