ARM64: dts: marvell: armada-37xx: Add clock resource for USB3

Now that clocks are available provide a clock resource for xhci node.
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>

arch/arm64/boot/dts/marvell/armada-37xx.dtsi

@@ -201,6 +201,7 @@ usb3: usb@58000 {
 				"generic-xhci";
 				reg = <0x58000 0x4000>;
 				interrupts = <GIC_SPI 3 IRQ_TYPE_LEVEL_HIGH>;
+				clocks = <&sb_periph_clk 12>;
 				status = "disabled";
 			};