ARM: Kirkwood: Fix missing clk for USB device.

Without the clock being held by a driver, it gets turned off at a bad
time causing the SoC to lockup. This is often during reboot.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Stefan Peter <s.peter@mpl.ch>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

arch/arm/boot/dts/kirkwood.dtsi

@@ -144,6 +144,7 @@ ehci@50000 {
 			compatible = "marvell,orion-ehci";
 			reg = <0x50000 0x1000>;
 			interrupts = <19>;
+			clocks = <&gate_clk 3>;
 			status = "okay";
 		};