Sound: remove direct access of driver_data

This is the last in-kernel direct usage of driver_data, replace it with
the proper dev_get/set_drvdata() calls.

Cc: Takashi Iwai <[e-mail]>
Cc: Jaroslav Kysela <[e-mail]>
Acked-by: Mark Brown <[e-mail]>
Cc: Liam Girdwood <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

sound/soc/codecs/wm8988.c

···
 	codec->control_data = spi;
 	codec->dev = &spi->dev;
 
-	spi->dev.driver_data = wm8988;
+	dev_set_drvdata(&spi->dev, wm8988);
 
 	return wm8988_register(wm8988);
 }
 
 static int __devexit wm8988_spi_remove(struct spi_device *spi)
 {
-	struct wm8988_priv *wm8988 = spi->dev.driver_data;
+	struct wm8988_priv *wm8988 = dev_get_drvdata(&spi->dev);
 
 	wm8988_unregister(wm8988);