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/pmac.c b/drivers/ide/pmac.c
index 904fb54..f5b85f4c 100644
--- a/drivers/ide/pmac.c
+++ b/drivers/ide/pmac.c
@@ -1432,7 +1432,7 @@
 	volatile struct dbdma_regs __iomem *dma = pmif->dma_regs;
 	struct scatterlist *sg;
 	int wr = (rq_data_dir(rq) == WRITE);
-	int i = hwif->sg_nents, count = 0;
+	int i = hwif->cmd.sg_nents, count = 0;
 
 	/* DMA table is already aligned */
 	table = (struct dbdma_cmd *) pmif->dma_table_cpu;