ASoC: fix ak4104 register array access

commit e555317c upstream.

Don't touch the variable 'reg' to construct the value for the actual SPI
transport. This variable is again used to access the driver's register
cache, and so random memory is overwritten.
Compute the value in-place instead.
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

sound/soc/codecs/ak4104.c

@@ -90,12 +90,10 @@ static int ak4104_spi_write(struct snd_soc_codec *codec, unsigned int reg,
 	if (reg >= codec->reg_cache_size)
 		return -EINVAL;
 
-	reg &= AK4104_REG_MASK;
-	reg |= AK4104_WRITE;
-
 	/* only write to the hardware if value has changed */
 	if (cache[reg] != value) {
-		u8 tmp[2] = { reg, value };
+		u8 tmp[2] = { (reg & AK4104_REG_MASK) | AK4104_WRITE, value };
+
 		if (spi_write(spi, tmp, sizeof(tmp))) {
 			dev_err(&spi->dev, "SPI write failed\n");
 			return -EIO;