mediatek-filogic: fix wax220 wifi leds

The WAX220 does have a 2.4GHz and 5GHz wifi led, which was set to trigger on netdev before.
This commit changes this to trigger on activity of the respective radio

Signed-off-by: Florian Maurer <f.maurer@outlook.de>
Link: https://github.com/openwrt/openwrt/pull/17627


Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
(cherry picked from commit 99431e31)