mediatek: store random MAC address in U-Boot env on first boot

For devboards without a MAC address assigned from factory, store
the random MAC in U-Boot env on first boot to make it persistent.

Signed-off-by: Daniel Golle <[email protected]>

target/linux/mediatek/base-files/etc/uci-defaults/99_fwenv-store-ethaddr.sh

@@ -0,0 +1,14 @@
+[ ! -e /etc/fw_env.config ] && exit 0
+
+. /lib/functions.sh
+
+case "$(board_name)" in
+bananapi,bpi-r2|\
+bananapi,bpi-r64|\
+unielec,u7623-02)
+	[ -z "$(fw_printenv -n ethaddr 2>/dev/null)" ] &&
+		fw_setenv ethaddr "$(cat /sys/class/net/eth0/address)"
+	;;
+esac
+
+exit 0