dmaengine: i.MX: Fix merge of cookie branch.

When merging DMA cookie changes a small chunk
of code was dropped. This broke imx-dma driver.

This patch adds this chunk again and fixes the problem.
Signed-off-by: Javier Martin <javier.martin@vista-silicon.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>

drivers/dma/imx-dma.c

@@ -679,6 +679,7 @@ static dma_cookie_t imxdma_tx_submit(struct dma_async_tx_descriptor *tx)
 	unsigned long flags;
 
 	spin_lock_irqsave(&imxdma->lock, flags);
+	list_move_tail(imxdmac->ld_free.next, &imxdmac->ld_queue);
 	cookie = dma_cookie_assign(tx);
 	spin_unlock_irqrestore(&imxdma->lock, flags);