ar71xx: add missing LED migration for Archer C7

When changing the LED names for the Archer C7 to represent the correct
color, a migration for existing UCI entries was not created.

Add a migration to keep existing LED configurations working.

Fixes commit c79c001b593b ("ar71xx: Archer C7 v1 LED names and RFKILL
fixes")

Signed-off-by: David Bauer <mail@david-bauer.net>
(cherry picked from commit 4349d4c6823bfe09caabbdd3c9a65198addc76d6)

target/linux/ar71xx/base-files/etc/uci-defaults/04_led_migration

@@ -44,6 +44,9 @@ migrate_leds()
 board=$(board_name)
 
 case "$board" in
+archer-c7)
+	migrate_leds ":blue:=:green:"
+	;;
 dhp-1565-a1|\
 dir-825-c1|\
 dir-835-a1)