arm64: zynqmp: Start usb ethernet gadget automatically

If only usb ethernet gadget is enabled it can start automatically.
If more gagdets are enabled usb ethernet gadget can be bind by
"bind /amba/usb1@ff9e0000/dwc3@fe300000 usb_ether" (on zcu100)

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

board/xilinx/zynqmp/zynqmp.c

@@ -544,6 +544,10 @@ int board_late_init(void)
 	char *env_targets;
 	int ret;
 
+#if defined(CONFIG_USB_ETHER) && !defined(CONFIG_USB_GADGET_DOWNLOAD)
+	usb_ether_init();
+#endif
+
 	if (!(gd->flags & GD_FLG_ENV_DEFAULT)) {
 		debug("Saved variables - Skipping\n");
 		return 0;