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/spi/spi-pl022.c b/drivers/spi/spi-pl022.c
index 1dc667f..a209f3b 100644
--- a/drivers/spi/spi-pl022.c
+++ b/drivers/spi/spi-pl022.c
@@ -1040,7 +1040,7 @@
 		goto err_tx_sgmap;
 
 	/* Send both scatterlists */
-	rxdesc = rxchan->device->device_prep_slave_sg(rxchan,
+	rxdesc = dmaengine_prep_slave_sg(rxchan,
 				      pl022->sgt_rx.sgl,
 				      rx_sglen,
 				      DMA_DEV_TO_MEM,
@@ -1048,7 +1048,7 @@
 	if (!rxdesc)
 		goto err_rxdesc;
 
-	txdesc = txchan->device->device_prep_slave_sg(txchan,
+	txdesc = dmaengine_prep_slave_sg(txchan,
 				      pl022->sgt_tx.sgl,
 				      tx_sglen,
 				      DMA_MEM_TO_DEV,