ASoC: qcom: qdsp6: Add support to Q6AFE

This patch adds support to Q6AFE (Audio Front End) module on Q6DSP.

AFE module sits right at the other end of cpu where the codec/audio
devices are connected.

AFE provides abstraced interfaces to both hardware and virtual devices.
Each AFE tx/rx port can be configured to connect to one of the hardware
devices like codec, hdmi, slimbus, i2s and so on. AFE services include
starting, stopping, and if needed, any configurations of the ports.

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