ASoC: wm8993: 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/wm8993.c

@@ -810,7 +810,7 @@ SOC_SINGLE_TLV("EQ5 Volume", WM8993_EQ6, 0, 24, 0, eq_tlv),
 static int clk_sys_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);
 
 	switch (event) {
 	case SND_SOC_DAPM_PRE_PMU: