ASoC: msm8916: Add codec Device Tree bindings.

ASoC: msm8916: Add codec Device Tree bindings.

This patch adds DT bindings required for msm8916 codec which is
integrated in msm8916 and apq8016 SOCs.

Codec IP is divided into two parts, first analog which is integrated
in pmic pm8916 and secondly digital part which is integrated into
application processor. Codec register controls are also split across
pmic an lpass. Analog part is controlled via spmi bus to pmic, registers
on the Application processor are memory mapped.

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