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/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index db7f88a..f9dcb53 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -483,7 +483,7 @@
 		return -EBUSY;
 	}
 
-	desc = dma_dev->device_prep_slave_sg(chan, &dmatx->sg, 1, DMA_MEM_TO_DEV,
+	desc = dmaengine_prep_slave_sg(chan, &dmatx->sg, 1, DMA_MEM_TO_DEV,
 					     DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 	if (!desc) {
 		dma_unmap_sg(dma_dev->dev, &dmatx->sg, 1, DMA_TO_DEVICE);
@@ -666,7 +666,6 @@
 static int pl011_dma_rx_trigger_dma(struct uart_amba_port *uap)
 {
 	struct dma_chan *rxchan = uap->dmarx.chan;
-	struct dma_device *dma_dev;
 	struct pl011_dmarx_data *dmarx = &uap->dmarx;
 	struct dma_async_tx_descriptor *desc;
 	struct pl011_sgbuf *sgbuf;
@@ -677,8 +676,7 @@
 	/* Start the RX DMA job */
 	sgbuf = uap->dmarx.use_buf_b ?
 		&uap->dmarx.sgbuf_b : &uap->dmarx.sgbuf_a;
-	dma_dev = rxchan->device;
-	desc = rxchan->device->device_prep_slave_sg(rxchan, &sgbuf->sg, 1,
+	desc = dmaengine_prep_slave_sg(rxchan, &sgbuf->sg, 1,
 					DMA_DEV_TO_MEM,
 					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 	/*