dt-bindings: adc-joystick: add poll-interval

Add poll-interval support for the adc-joystick documentation. This is
an optional value and if not provided the adc-joystick works as it
does today (with buffers). If this value is provided, the adc-joystick
driver is polled at the specified interval. The existing attribute of
"poll-interval" was used instead of complying with property-units.yaml
after discussion of the issue on the mailing list.

Signed-off-by: Maya Matuszczyk <maccraft123mc@gmail.com>
Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Artur Rojek <contact@artur-rojek.eu>
Link: https://lore.kernel.org/r/20220816210440.14260-2-macroalpha82@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/adc-joystick.yaml

@@ -14,6 +14,9 @@ description: >
   Bindings for joystick devices connected to ADC controllers supporting
   the Industrial I/O subsystem.
 
+allOf:
+  - $ref: input.yaml#
+
 properties:
   compatible:
     const: adc-joystick
@@ -28,6 +31,8 @@ properties:
       https://github.com/devicetree-org/dt-schema/blob/master/schemas/iio/iio-consumer.yaml
       for details.
 
+  poll-interval: true
+
   '#address-cells':
     const: 1