ARM: dts: imx53: Fix 'usbphy@x' node with unit name and no reg property

The following build warnings are seen with W=1:

Warning (unit_address_vs_reg): Node /soc/aips@50000000/usbphy@0 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/aips@50000000/usbphy@1 has a unit name, but no reg property

Fix these warnings by changing '@' to '-'.
Signed-off-by: Marco Franchi <marco.franchi@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx53.dtsi

@@ -299,14 +299,14 @@ aipstz1: bridge@53f00000 {
 				reg = <0x53f00000 0x60>;
 			};
 
-			usbphy0: usbphy@0 {
+			usbphy0: usbphy-0 {
 				compatible = "usb-nop-xceiv";
 				clocks = <&clks IMX5_CLK_USB_PHY1_GATE>;
 				clock-names = "main_clk";
 				status = "okay";
 			};
 
-			usbphy1: usbphy@1 {
+			usbphy1: usbphy-1 {
 				compatible = "usb-nop-xceiv";
 				clocks = <&clks IMX5_CLK_USB_PHY2_GATE>;
 				clock-names = "main_clk";