dt-bindings: pwm: rockchip: Add rockchip,rk3128-pwm

Add rockchip,rk3128-pwm compatible string.
Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

Documentation/devicetree/bindings/pwm/pwm-rockchip.yaml

@@ -21,6 +21,7 @@ properties:
           - const: rockchip,rk2928-pwm
       - items:
           - enum:
+              - rockchip,rk3128-pwm
               - rockchip,rk3368-pwm
               - rockchip,rk3399-pwm
               - rockchip,rv1108-pwm