ASoC: tlv320adcx140: Remove undocumented property

Remove undocumented and unneeded ti,use-internal-reg from the example as
it was an artifact from initial development.  The code does not query
for this property and as the document indicates if areg-supply is
undefined then the internal regulator is used.

Fixes: 302c0b7490cd ("dt-bindings: sound: Add TLV320ADCx140 dt
bindings")
Signed-off-by: Dan Murphy <dmurphy@ti.com>
CC: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200327162432.17067-1-dmurphy@ti.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/tlv320adcx140.yaml

@@ -76,7 +76,6 @@ examples:
       codec: codec@4c {
         compatible = "ti,tlv320adc5140";
         reg = <0x4c>;
-        ti,use-internal-areg;
         ti,mic-bias-source = <6>;
         reset-gpios = <&gpio0 14 GPIO_ACTIVE_HIGH>;
       };