dt-bindings: arm: rockchip: add more compatible strings to pmu.yaml

The compatible strings below are already in use in the Rockchip
dtsi files, but were somehow never added to a document, so add

"rockchip,px30-pmu", "syscon", "simple-mfd"
"rockchip,rk3288-pmu", "syscon", "simple-mfd"
"rockchip,rk3399-pmu", "syscon", "simple-mfd"

for pmu nodes to pmu.yaml.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210417112952.8516-13-jbx6244@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

Author: Johan Jonker

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

@@ -19,7 +19,10 @@ select:
     compatible:
       contains:
         enum:
+          - rockchip,px30-pmu
           - rockchip,rk3066-pmu
+          - rockchip,rk3288-pmu
+          - rockchip,rk3399-pmu
 
   required:
     - compatible
@@ -28,7 +31,10 @@ properties:
   compatible:
     items:
       - enum:
+          - rockchip,px30-pmu
           - rockchip,rk3066-pmu
+          - rockchip,rk3288-pmu
+          - rockchip,rk3399-pmu
       - const: syscon
       - const: simple-mfd