spi: tegra: Use DIV_ROUND_UP instead of open coded

This also makes the intention more clear.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
diff --git a/drivers/spi/spi-tegra20-sflash.c b/drivers/spi/spi-tegra20-sflash.c
index 1d814dc..64c9cf5 100644
--- a/drivers/spi/spi-tegra20-sflash.c
+++ b/drivers/spi/spi-tegra20-sflash.c
@@ -173,7 +173,7 @@
 	unsigned remain_len = t->len - tsd->cur_pos;
 	unsigned max_word;
 
-	tsd->bytes_per_word = (t->bits_per_word - 1) / 8 + 1;
+	tsd->bytes_per_word = DIV_ROUND_UP(t->bits_per_word, 8);
 	max_word = remain_len / tsd->bytes_per_word;
 	if (max_word > SPI_FIFO_DEPTH)
 		max_word = SPI_FIFO_DEPTH;