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/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index a09c06b..c55f966 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -413,7 +413,7 @@
 		return -EINVAL;
 
 	dmaengine_slave_config(chan, &conf);
-	desc = device->device_prep_slave_sg(chan, data->sg, nr_sg,
+	desc = dmaengine_prep_slave_sg(chan, data->sg, nr_sg,
 					    conf.direction, DMA_CTRL_ACK);
 	if (!desc)
 		goto unmap_exit;