dt-bindings: phy-rockchip-inno-usb2: add assign clock property in usb2-phy node

On some platform such as RK3328, the 480m clock may need to assign
clock parent in dts in stead of clock driver. So this patch add
property of assigned-clocks and assigned-clock-parents to assign
parent for 480m clock.
Signed-off-by: Meng Dongyang <daniel.meng@rock-chips.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

Documentation/devicetree/bindings/phy/phy-rockchip-inno-usb2.txt

@@ -2,6 +2,7 @@ ROCKCHIP USB2.0 PHY WITH INNO IP BLOCK
 
 Required properties (phy (parent) node):
  - compatible : should be one of the listed compatibles:
+	* "rockchip,rk3328-usb2phy"
 	* "rockchip,rk3366-usb2phy"
 	* "rockchip,rk3399-usb2phy"
  - reg : the address offset of grf for usb-phy configuration.
@@ -11,6 +12,11 @@ Required properties (phy (parent) node):
 Optional properties:
  - clocks : phandle + phy specifier pair, for the input clock of phy.
  - clock-names : input clock name of phy, must be "phyclk".
+ - assigned-clocks : phandle of usb 480m clock.
+ - assigned-clock-parents : parent of usb 480m clock, select between
+		 usb-phy output 480m and xin24m.
+		 Refer to clk/clock-bindings.txt for generic clock
+		 consumer properties.
 
 Required nodes : a sub-node is required for each port the phy provides.
 		 The sub-node name is used to identify host or otg port,