ipq806x: use switch trigger for WAN LED on NETGEAR boards

With this commit, the WAN LED is triggered by the switch port state
instead of the eth0 netdev.
Otherwise, the LED is always illuminated, regardless of the WAN port
link state.

Signed-off-by: David Bauer <mail@david-bauer.net>
(cherry picked from commit 70d5989c9c)
Signed-off-by: David Bauer <mail@david-bauer.net>

target/linux/ipq806x/base-files/etc/board.d/01_leds

@@ -30,7 +30,7 @@ netgear,r7500v2 |\
 netgear,r7800)
 	ucidef_set_led_usbport "usb1" "USB 1" "${boardname}:white:usb1" "usb1-port1" "usb2-port1"
 	ucidef_set_led_usbport "usb2" "USB 2" "${boardname}:white:usb2" "usb3-port1" "usb4-port1"
-	ucidef_set_led_netdev "wan" "WAN" "${boardname}:white:wan" "eth0"
+	ucidef_set_led_switch "wan" "WAN" "${boardname}:white:wan" "switch0" "0x20"
 	ucidef_set_led_ide "esata" "eSATA" "${boardname}:white:esata"
 	;;
 tplink,c2600)