dmaengine: dw: define DW_DMA_MAX_NR_MASTERS

Instead of using magic number in the code the patch provides
DW_DMA_MAX_NR_MASTERS constant.

While here, restrict the reading of data width array by amount of the actual
number of AHB masters.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/dw/regs.h

@@ -285,7 +285,7 @@ struct dw_dma {
 
 	/* hardware configuration */
 	unsigned char		nr_masters;
-	unsigned char		data_width[4];
+	unsigned char		data_width[DW_DMA_MAX_NR_MASTERS];
 };
 
 static inline struct dw_dma_regs __iomem *__dw_regs(struct dw_dma *dw)