ASoC: Add snd_soc_kcontrol_codec() helper function

For CODEC controls snd_kcontrol_chip() currently returns a pointer to the
CODEC that registered the control. With the upcoming consolidation of
platform and CODEC controls this will change. Prepare for this by introducing
the snd_soc_kcontrol_codec() helper function that will hide the implementation
details of how the CODEC for a control can be obtained. This will allow us to
change this easily in the future.

The patch also updates all CODEC drivers to use the new helper function.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/codecs/tlv320aic23.c

@@ -82,7 +82,7 @@ static const DECLARE_TLV_DB_SCALE(sidetone_vol_tlv, -1800, 300, 0);
 static int snd_soc_tlv320aic23_put_volsw(struct snd_kcontrol *kcontrol,
 	struct snd_ctl_elem_value *ucontrol)
 {
-	struct snd_soc_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct snd_soc_codec *codec = snd_soc_kcontrol_codec(kcontrol);
 	u16 val, reg;
 
 	val = (ucontrol->value.integer.value[0] & 0x07);
@@ -105,7 +105,7 @@ static int snd_soc_tlv320aic23_put_volsw(struct snd_kcontrol *kcontrol,
 static int snd_soc_tlv320aic23_get_volsw(struct snd_kcontrol *kcontrol,
 	struct snd_ctl_elem_value *ucontrol)
 {
-	struct snd_soc_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct snd_soc_codec *codec = snd_soc_kcontrol_codec(kcontrol);
 	u16 val;
 
 	val = snd_soc_read(codec, TLV320AIC23_ANLG) & (0x1C0);