ASoC: qcom: common: Parse "pin-switches" and "widgets" from DT

Use the DT helpers in the ASoC core to parse the "pin-switches" and
"widgets" properties from the device tree. This allows adding extra
mixers to disable e.g. an extra speaker amplifier that would be
normally powered on automatically because it is connected to a shared
output pin.

Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Link: https://lore.kernel.org/r/20211214142049.20422-4-stephan@gerhold.net
Signed-off-by: Mark Brown <broonie@kernel.org>