spi: bcm2835: Use SPI_BPW_MASK macro for bits_per_word_mask setting

We have a SPI_BPW_MASK macro defined in spi.h, use it instead of open-coded.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 7604c52..7de617a 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -314,7 +314,7 @@
 	platform_set_drvdata(pdev, master);
 
 	master->mode_bits = BCM2835_SPI_MODE_BITS;
-	master->bits_per_word_mask = BIT(8 - 1);
+	master->bits_per_word_mask = SPI_BPW_MASK(8);
 	master->bus_num = -1;
 	master->num_chipselect = 3;
 	master->transfer_one_message = bcm2835_spi_transfer_one;