DMAENGINE: extend the control command to include an arg

This adds an argument to the DMAengine control function, so that
we can later provide control commands that need some external data
passed in through an argument akin to the ioctl() operation
prototype.

[dan.j.williams@intel.com: fix up some missed conversions]
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 50b7b3e..1745657 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -347,7 +347,8 @@
 		struct dma_chan *chan, struct scatterlist *sgl,
 		unsigned int sg_len, enum dma_data_direction direction,
 		unsigned long flags);
-	int (*device_control)(struct dma_chan *chan, enum dma_ctrl_cmd cmd);
+	int (*device_control)(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
+		unsigned long arg);
 
 	enum dma_status (*device_tx_status)(struct dma_chan *chan,
 					    dma_cookie_t cookie,