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>
diff --git a/board/xilinx/zynqmp/zynqmp.c b/board/xilinx/zynqmp/zynqmp.c
index 168cf5c..13c404b 100644
--- a/board/xilinx/zynqmp/zynqmp.c
+++ b/board/xilinx/zynqmp/zynqmp.c
@@ -543,6 +543,10 @@
 	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;