ath79: fix rssi-low LED for My Net Range Extender

The LED color was missing in 01_leds.

Fixes: 745dee11ac ("ath79: add support for WD My Net Wi-Fi Range
Extender")

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
(cherry picked from commit d232a8ac7d1679f7ff97cbc66b4c49c940bd009f)

target/linux/ath79/base-files/etc/board.d/01_leds

@@ -253,7 +253,7 @@ ubnt,nanostation-ac)
 wd,mynet-wifi-rangeextender)
 	ucidef_set_led_netdev "lan" "LAN" "$boardname:green:lan" "eth0"
 	ucidef_set_rssimon "wlan0" "200000" "1"
-	ucidef_set_led_rssi "rssilow" "RSSILOW" "$boardname:rssi-low" "wlan0" "1" "100"
+	ucidef_set_led_rssi "rssilow" "RSSILOW" "$boardname:blue:rssi-low" "wlan0" "1" "100"
 	ucidef_set_led_rssi "rssimedium" "RSSIMED" "$boardname:blue:rssi-med" "wlan0" "33" "100"
 	ucidef_set_led_rssi "rssihigh" "RSSIMAX" "$boardname:blue:rssi-max" "wlan0" "66" "100"
 	;;