mediatek: filogic: set wan label in preinit

Implement the functionality of
target/linux/ramips/patches-5.15/700-net-ethernet-mediatek-support-net-labels.patch
in userspace, since the driver patch has been rejected as a generic solution:
https://github.com/openwrt/openwrt/pull/11435

Signed-off-by: Bjørn Mork <bjorn@mork.no>
(cherry picked from commit 1dd1ac2c35)

target/linux/mediatek/filogic/base-files/lib/preinit/04_set_netdev_label

@@ -0,0 +1,15 @@
+set_netdev_labels() {
+	local dir
+	local label
+	local netdev
+
+	for dir in /sys/class/net/*; do
+		[ -r "$dir/of_node/label" ] || continue
+		label="$(cat "$dir/of_node/label")"
+		netdev="$(basename $dir)"
+		[ "$netdev" = "$label" ] && continue
+		ip link set "$netdev" name "$label"
+	done
+}
+
+boot_hook_add preinit_main set_netdev_labels