ARM: dts: bcm283x: Fix DTC warnings about missing phy-cells

This patch fixes the DTC warnings about missing property #phy-cells.
Signed-off-by: NStefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: NEric Anholt <eric@anholt.net>
Reviewed-by: NEric Anholt <eric@anholt.net>

arch/arm/boot/dts/bcm283x.dtsi

@@ -639,5 +639,6 @@
 
 	usbphy: phy {
 		compatible = "usb-nop-xceiv";
+		#phy-cells = <0>;
 	};
 };