dt-bindings: arm: rockchip: add rk3368 compatible string to pmu.yaml

Add the compatible for the pmu mfd on rk3368.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210925090405.2601792-1-heiko@sntech.de

Documentation/devicetree/bindings/arm/rockchip/pmu.yaml

@@ -22,6 +22,7 @@ select:
           - rockchip,px30-pmu
           - rockchip,rk3066-pmu
           - rockchip,rk3288-pmu
+          - rockchip,rk3368-pmu
           - rockchip,rk3399-pmu
           - rockchip,rk3568-pmu
 
@@ -35,6 +36,7 @@ properties:
           - rockchip,px30-pmu
           - rockchip,rk3066-pmu
           - rockchip,rk3288-pmu
+          - rockchip,rk3368-pmu
           - rockchip,rk3399-pmu
           - rockchip,rk3568-pmu
       - const: syscon