dt-bindings: rockchip: grf: add grf and pmugrf description for px30

This patch adds the compatible of GRF and PMUGRF for PX30 SoCs.
Signed-off-by: Liang Chen <cl@rock-chips.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

Documentation/devicetree/bindings/soc/rockchip/grf.txt

@@ -13,6 +13,7 @@ On RK3328 SoCs, the GRF adds a section for USB2PHYGRF,
 Required Properties:
 
 - compatible: GRF should be one of the following:
+   - "rockchip,px30-grf", "syscon": for px30
    - "rockchip,rk3036-grf", "syscon": for rk3036
    - "rockchip,rk3066-grf", "syscon": for rk3066
    - "rockchip,rk3188-grf", "syscon": for rk3188
@@ -23,6 +24,7 @@ Required Properties:
    - "rockchip,rk3399-grf", "syscon": for rk3399
    - "rockchip,rv1108-grf", "syscon": for rv1108
 - compatible: PMUGRF should be one of the following:
+   - "rockchip,px30-pmugrf", "syscon": for px30
    - "rockchip,rk3368-pmugrf", "syscon": for rk3368
    - "rockchip,rk3399-pmugrf", "syscon": for rk3399
 - compatible: SGRF should be one of the following