ASoC: wm9712: Fix build due to missing definition of "runtime"

Fix the following build error:

sound/soc/codecs/wm9712.c:482:32: error: 'runtime' undeclared (first use in this function)
sound/soc/codecs/wm9712.c:499:33: error: 'runtime' undeclared (first use in this function)
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/codecs/wm9712.c

@@ -470,6 +470,7 @@ static int ac97_prepare(struct snd_pcm_substream *substream,
 	struct snd_soc_codec *codec = dai->codec;
 	int reg;
 	u16 vra;
+	struct snd_pcm_runtime *runtime = substream->runtime;
 
 	vra = ac97_read(codec, AC97_EXTENDED_STATUS);
 	ac97_write(codec, AC97_EXTENDED_STATUS, vra | 0x1);
@@ -487,6 +488,7 @@ static int ac97_aux_prepare(struct snd_pcm_substream *substream,
 {
 	struct snd_soc_codec *codec = dai->codec;
 	u16 vra, xsle;
+	struct snd_pcm_runtime *runtime = substream->runtime;
 
 	vra = ac97_read(codec, AC97_EXTENDED_STATUS);
 	ac97_write(codec, AC97_EXTENDED_STATUS, vra | 0x1);