ASoC: dt-bindings: wcd93xx: add bindings for audio mux controlling hp

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-controls so that both the gpio and regulators can be
driven correctly, rather than adding regulator handing in the codec.

This patch adds required bindings to add such mux controls.

Signed-off-by: Srinivas Kandagatla <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/sound/qcom,wcd938x.yaml

···
       - qcom,wcd9380-codec
       - qcom,wcd9385-codec
 
+  mux-controls:
+    description: A reference to the audio mux switch for
+      switching CTIA/OMTP Headset types
+    maxItems: 1
+
   us-euro-gpios:
     description: GPIO spec for swapping gnd and mic segments
     maxItems: 1
+    deprecated: true
 
 required:
   - compatible