regulator: dt-bindings: rpi-panel: Mark 7" Raspberry Pi as GPIO controller

Mark the Raspberry Pi 7" Display 1 ATTINY based regulator
as GPIO controller, because the hardware behaves that way
in addition to being a regulator. Add fixed gpio-cells as
well.

Signed-off-by: Marek Vasut <marex@nabladev.com>
Link: https://patch.msgid.link/20260107213638.505319-1-marex@nabladev.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Marek Vasut

Documentation/devicetree/bindings/regulator/raspberrypi,7inch-touchscreen-panel-regulator.yaml

@@ -24,6 +24,11 @@ properties:
   reg:
     maxItems: 1
 
+  gpio-controller: true
+
+  "#gpio-cells":
+    const: 2
+
 additionalProperties: false
 
 required: