ipq40xx: remove model name from LED labels

Like in the previous patches for ath79 and ramips, this will remove
the "devicename" from LED labels in ipq40xx.

The devicename is removed in DTS files and 01_leds, and a migration
script is added. While at it, also harmonize capitalization of
wlan2G/wlan5G vs. wlan2g/wlan5g.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

target/linux/ipq40xx/base-files/etc/uci-defaults/04_led_migration

@@ -0,0 +1,19 @@
+. /lib/functions/migrations.sh
+
+board=$(board_name)
+
+case "$board" in
+engenius,emr3500)
+	migrate_leds "emr3500:="
+	;;
+engenius,ens620ext|\
+zyxel,nbg6617)
+	migrate_leds ":wlan2G=:wlan2g" ":wlan5G=:wlan5g"
+	;;
+esac
+
+remove_devicename_leds
+
+migrations_apply system
+
+exit 0