Enable networking and console over the USB port

That one is much more friendly than the UART0 pin header.

Change-Id: I76affd2803eb2f18911eb71cbdfc1ffd6bf4fd76
diff --git a/board/czechlight/common/overlay/etc/modules-load.d/usb-serial-gadget.conf b/board/czechlight/common/overlay/etc/modules-load.d/usb-serial-gadget.conf
new file mode 100644
index 0000000..41c481d
--- /dev/null
+++ b/board/czechlight/common/overlay/etc/modules-load.d/usb-serial-gadget.conf
@@ -0,0 +1,2 @@
+# composite module for serial console and Ethernet over the miniUSB port
+g_cdc