dmaengine: move last completed cookie into generic dma_chan structure

Every DMA engine implementation declares a last completed dma cookie
in their private dma channel structures.  This is pointless, and
forces driver specific code.  Move this out into the common dma_chan
structure.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Jassi Brar <jassisinghbrar@gmail.com>
[imx-sdma.c & mxs-dma.c]
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
diff --git a/drivers/dma/sirf-dma.c b/drivers/dma/sirf-dma.c
index 2333810..60473f0 100644
--- a/drivers/dma/sirf-dma.c
+++ b/drivers/dma/sirf-dma.c
@@ -59,7 +59,6 @@
 	struct list_head		queued;
 	struct list_head		active;
 	struct list_head		completed;
-	dma_cookie_t			completed_cookie;
 	unsigned long			happened_cyclic;
 	unsigned long			completed_cyclic;
 
@@ -208,7 +207,7 @@
 			/* Free descriptors */
 			spin_lock_irqsave(&schan->lock, flags);
 			list_splice_tail_init(&list, &schan->free);
-			schan->completed_cookie = last_cookie;
+			schan->chan.completed_cookie = last_cookie;
 			spin_unlock_irqrestore(&schan->lock, flags);
 		} else {
 			/* for cyclic channel, desc is always in active list */
@@ -419,7 +418,7 @@
 
 	spin_lock_irqsave(&schan->lock, flags);
 	last_used = schan->chan.cookie;
-	last_complete = schan->completed_cookie;
+	last_complete = schan->chan.completed_cookie;
 	spin_unlock_irqrestore(&schan->lock, flags);
 
 	dma_set_tx_state(txstate, last_complete, last_used, 0);
@@ -636,7 +635,7 @@
 
 		schan->chan.device = dma;
 		schan->chan.cookie = 1;
-		schan->completed_cookie = schan->chan.cookie;
+		schan->chan.completed_cookie = schan->chan.cookie;
 
 		INIT_LIST_HEAD(&schan->free);
 		INIT_LIST_HEAD(&schan->prepared);