spi/bcm63xx: check spi bits_per_word in spi_setup

Instead of fixing up the bits_per_word (which the spi subsystem already
does for us), check it for supported values.
Signed-off-by: Jonas Gorski <jogo@openwrt.org>
Acked-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/spi/spi-bcm63xx.c

@@ -151,8 +151,11 @@ static void bcm63xx_spi_setup_transfer(struct spi_device *spi,
 
 static int bcm63xx_spi_setup(struct spi_device *spi)
 {
-	if (!spi->bits_per_word)
-		spi->bits_per_word = 8;
+	if (spi->bits_per_word != 8) {
+		dev_err(&spi->dev, "%s, unsupported bits_per_word=%d\n",
+			__func__, spi->bits_per_word);
+		return -EINVAL;
+	}
 
 	return 0;
 }