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>

drivers/dma/ste_dma40.c

@@ -2065,7 +2065,8 @@ static void d40_issue_pending(struct dma_chan *chan)
 	spin_unlock_irqrestore(&d40c->lock, flags);
 }
 
-static int d40_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd)
+static int d40_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
+		       unsigned long arg)
 {
 	unsigned long flags;
 	struct d40_chan *d40c = container_of(chan, struct d40_chan, chan);