ASoC: dt-bindings: tlv320adc3xxx: Add MICBIAS-as-GPO properties

Add properties for configuring the MICBIAS pins as general purpose
outputs, with some limitations: The voltage on the pin when activated
may be set using another property to 2.0 V, 2.5 V or AVDD.
When deactivated the pin will float.

Signed-off-by: Ricard Wanderlof <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Link: https://msgid.link/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/sound/ti,tlv320adc3xxx.yaml

···
       Note that there is currently no support for reading the GPIO pins as
       inputs.
 
+  ti,micbias1-gpo:
+    type: boolean
+    description: |
+      When set, the MICBIAS1 pin may be controlled via the GPIO framework,
+      as pin number 3 on the device.
+
+      In this mode, when the pin is activated, it will be set to the voltage
+      specified by the ti,micbias1-vg property. When deactivated, the pin will
+      float.
+
+  ti,micbias2-gpo:
+    type: boolean
+    description: |
+      When set, the MICBIAS2 pin may be controlled via the GPIO framework,
+      as pin number 4 on the device.
+
+      In this mode, when the pin is activated, it will be set to the voltage
+      specified by the ti,micbias2-vg property. When deactivated, the pin will
+      float.
+
   ti,micbias1-vg:
     $ref: /schemas/types.yaml#/definitions/uint32
     enum:
···
     default: 0
     description: |
       Mic bias voltage output on MICBIAS2 pin
+
+dependencies:
+  ti,micbias1-gpo: ['ti,micbias1-vg']
+  ti,micbias2-gpo: ['ti,micbias2-vg']
 
 required:
   - compatible