dmaengine: add context parameter to prep_slave_sg and prep_dma_cyclic

Add context parameter to device_prep_slave_sg() and device_prep_dma_cyclic()
interfaces to allow passing client/target specific information associated
with the data transfer.
Modify all affected DMA engine drivers.

Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
index cb173bb..7439079 100644
--- a/drivers/dma/dw_dmac.c
+++ b/drivers/dma/dw_dmac.c
@@ -704,7 +704,7 @@
 static struct dma_async_tx_descriptor *
 dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 		unsigned int sg_len, enum dma_transfer_direction direction,
-		unsigned long flags)
+		unsigned long flags, void *context)
 {
 	struct dw_dma_chan	*dwc = to_dw_dma_chan(chan);
 	struct dw_dma_slave	*dws = chan->private;