ASoC: codecs: wcd938x: add mux control support for hp audio mux

ASoC: codecs: wcd938x: add mux control support for hp audio mux

On some platforms to minimise pop and click during switching between
CTIA and OMTP headset an additional HiFi mux is used. Most common
case is that this switch is switched on by default, but on some
platforms this needs a regulator enable.

move to using mux control to enable both regulator and handle gpios,
deprecate the usage of gpio.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Tested-by: Christopher Obbard <christopher.obbard@linaro.org>
Tested-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Link: https://patch.msgid.link/20250327100633.11530-6-srinivas.kandagatla@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>