zynq-topic-miami.dts: Add usbotg0 alias to make USB actually work

Fixes the following problem:
zynq-uboot> run dfu_ram
Setting bus to 1
g_dnl_register: failed!, error: -19

The cause appears to be that the USB framework is looking for a usbotg aliases,
so add the alias to point to our USB device.
Signed-off-by: NMike Looijmans <mike.looijmans@topic.nl>
Signed-off-by: NMichal Simek <michal.simek@xilinx.com>

arch/arm/dts/zynq-topic-miami.dts

@@ -19,6 +19,7 @@
 		i2c0 = &i2c0;
 		i2c1 = &i2c1;
 		mmc0 = &sdhci0;
+		usbotg0 = &usb0;
 	};
 
 	memory@0 {