sound: codec: Add support to msm8x16_wcd codec.

On msm8x16 SOCs the codec integration is split into digital and analog
parts, digitial part is integrated with SOC and the analog part is
integrated as part of pmic chip pm8916.

This driver provides basic playback support with lot of todos:
1> Capture support
2> Cleanup
3> Multi button head set support.
4> Impedenace matching logic.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>