dmaengine/dma_slave: introduce inline wrappers

Add inline wrappers for device_prep_slave_sg() and device_prep_dma_cyclic()
interfaces to hide new parameter from current users of affected interfaces.
Convert current users to use new wrappers instead of direct calls.
Suggested by Russell King [https://lkml.org/lkml/2012/2/3/269].

Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 7508579..872557f 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1338,7 +1338,7 @@
 		struct scatterlist *sg = &s->sg_rx[i];
 		struct dma_async_tx_descriptor *desc;
 
-		desc = chan->device->device_prep_slave_sg(chan,
+		desc = dmaengine_prep_slave_sg(chan,
 			sg, 1, DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT);
 
 		if (desc) {
@@ -1453,7 +1453,7 @@
 
 	BUG_ON(!sg_dma_len(sg));
 
-	desc = chan->device->device_prep_slave_sg(chan,
+	desc = dmaengine_prep_slave_sg(chan,
 			sg, s->sg_len_tx, DMA_MEM_TO_DEV,
 			DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 	if (!desc) {