IDE: sg chaining support

Acked-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/ide/ide-dma.c b/drivers/ide/ide-dma.c
index b453211..a4cbbba 100644
--- a/drivers/ide/ide-dma.c
+++ b/drivers/ide/ide-dma.c
@@ -280,7 +280,7 @@
 			}
 		}
 
-		sg++;
+		sg = sg_next(sg);
 		i--;
 	}