ASoC: wm8904: 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/wm8904.c

@@ -673,7 +673,7 @@ static int cp_event(struct snd_soc_dapm_widget *w,
 static int sysclk_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);
 	struct wm8904_priv *wm8904 = snd_soc_codec_get_drvdata(codec);
 
 	switch (event) {
@@ -711,7 +711,7 @@ static int sysclk_event(struct snd_soc_dapm_widget *w,
 static int out_pga_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);
 	struct wm8904_priv *wm8904 = snd_soc_codec_get_drvdata(codec);
 	int reg, val;
 	int dcs_mask;