ASoC: wm8900: Replace w->codec snd_soc_dapm_to_codec(w->dapm)

The codec field of the snd_soc_widget struct is eventually going to be
removed, use snd_soc_dapm_to_codec(w->dapm) instead.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/wm8900.c

@@ -224,7 +224,7 @@ static void wm8900_reset(struct snd_soc_codec *codec)
 static int wm8900_hp_event(struct snd_soc_dapm_widget *w,
 			   struct snd_kcontrol *kcontrol, int event)
 {
-	struct snd_soc_codec *codec = w->codec;
+	struct snd_soc_codec *codec = snd_soc_dapm_to_codec(w->dapm);
 	u16 hpctl1 = snd_soc_read(codec, WM8900_REG_HPCTL1);
 
 	switch (event) {