ARM: at91/dt: remove useless usb clock

The ohci driver now calls clk_set_rate on the uhpck clock (which forwards
set_rate requests to its parent: the usb clock).
Remove useless references to usb clocks from ohci definitions.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/boot/dts/at91sam9n12.dtsi

@@ -949,9 +949,8 @@
 			compatible = "atmel,at91rm9200-ohci", "usb-ohci";
 			reg = <0x00500000 0x00100000>;
 			interrupts = <22 IRQ_TYPE_LEVEL_HIGH 2>;
-			clocks = <&usb>, <&uhphs_clk>, <&uhphs_clk>,
-				 <&uhpck>;
-			clock-names = "usb_clk", "ohci_clk", "hclk", "uhpck";
+			clocks = <&uhphs_clk>, <&uhphs_clk>, <&uhpck>;
+			clock-names = "ohci_clk", "hclk", "uhpck";
 			status = "disabled";
 		};
 	};