ASoC: sta350: Use snd_soc_kcontrol_codec()

In preparation for componentisation of the kcontrol helpers use
snd_soc_kcontrol_codec() instead of snd_kcontrol_chip().

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>