ramips: use tpt DTS trigger for TP-Link TL-MR3020 v3 and TL-WA801ND v5

ramips: use tpt DTS trigger for TP-Link TL-MR3020 v3 and TL-WA801ND v5

This converts the TP-Link TL-MR3020v3 board to use the WLAN throughput
LED trigger in order to react to all VAPs.

It also moves the WLAN trigger config of the TP-Link TL-WA801NDv5 to the
DTS and merges the now identical LAN LED configs.

Verified these changes on a TL-MR3020v3.

Signed-off-by: Jan Alexander <jan@nalx.net>
[changed commit title and extended commit message]
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>