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 <[e-mail]>
Tested-by: Stefan Peter <[e-mail]>
Signed-off-by: Jason Cooper <[e-mail]>

arch/arm/boot/dts/kirkwood.dtsi

···
 			compatible = "marvell,orion-ehci";
 			reg = <0x50000 0x1000>;
 			interrupts = <19>;
+			clocks = <&gate_clk 3>;
 			status = "okay";
 		};