dt-bindings: pinctrl: samsung: Add compatible for ARTPEC-9 SoC

Document the compatible string for ARTPEC-9 SoC pinctrl block,
which is similar to other Samsung SoC pinctrl blocks.

Signed-off-by: SeonGu Kang <ksk4725@coasia.com>
Signed-off-by: Ravi Patel <ravi.patel@samsung.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Author: ksk4725

Documentation/devicetree/bindings/pinctrl/samsung,pinctrl.yaml

@@ -36,6 +36,7 @@ properties:
   compatible:
     enum:
       - axis,artpec8-pinctrl
+      - axis,artpec9-pinctrl
       - google,gs101-pinctrl
       - samsung,s3c64xx-pinctrl
       - samsung,s5pv210-pinctrl