dma: dw: allocate memory in two stages in probe

This makes the probe() function a little bit clearer.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
diff --git a/drivers/dma/dw/regs.h b/drivers/dma/dw/regs.h
index deb4274..bb98d3e 100644
--- a/drivers/dma/dw/regs.h
+++ b/drivers/dma/dw/regs.h
@@ -252,13 +252,13 @@
 	struct tasklet_struct	tasklet;
 	struct clk		*clk;
 
+	/* channels */
+	struct dw_dma_chan	*chan;
 	u8			all_chan_mask;
 
 	/* hardware configuration */
 	unsigned char		nr_masters;
 	unsigned char		data_width[4];
-
-	struct dw_dma_chan	chan[0];
 };
 
 static inline struct dw_dma_regs __iomem *__dw_regs(struct dw_dma *dw)