spi: dw-mid: change magic numbers to the constants

Instead of using magic numbers in the code we create a bit map definition of
the DMACR register and use it.

There is no functional change.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-dw-mid.c

@@ -124,9 +124,9 @@ static int mid_spi_dma_transfer(struct dw_spi *dws, int cs_change)
 		dw_writew(dws, DW_SPI_DMARDLR, 0xf);
 		dw_writew(dws, DW_SPI_DMATDLR, 0x10);
 		if (dws->tx_dma)
-			dma_ctrl |= 0x2;
+			dma_ctrl |= SPI_DMA_TDMAE;
 		if (dws->rx_dma)
-			dma_ctrl |= 0x1;
+			dma_ctrl |= SPI_DMA_RDMAE;
 		dw_writew(dws, DW_SPI_DMACR, dma_ctrl);
 		spi_enable_chip(dws, 1);
 	}

drivers/spi/spi-dw.h

@@ -74,6 +74,10 @@
 #define SPI_INT_RXFI			(1 << 4)
 #define SPI_INT_MSTI			(1 << 5)
 
+/* Bit fields in DMACR */
+#define SPI_DMA_RDMAE			(1 << 0)
+#define SPI_DMA_TDMAE			(1 << 1)
+
 /* TX RX interrupt level threshold, max can be 256 */
 #define SPI_INT_THRESHOLD		32