dt-bindings: iio: accel: kxcjk1013: Document regulator supplies

kxcjk1013 devices have VDD and VDDIO power lines. Need
to make sure the regulators are enabled before any
communication with kxcjk1013. Document support for
vdd/vddio-supply to implement this.
Signed-off-by: Devajith V S <devajithvs@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201213172437.2779-1-devajithvs@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/accel/kionix,kxcjk1013.yaml

@@ -20,6 +20,9 @@ properties:
   reg:
     maxItems: 1
 
+  vdd-supply: true
+  vddio-supply: true
+
   mount-matrix:
     description: an optional 3x3 mounting rotation matrix.