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 and TL-WA801NDv5.

Signed-off-by: Jan Alexander <jan@nalx.net>
[changed commit title and extended commit message]
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
[added comment about test result on TL-WA801ND v5]
Signed-off-by: David Bauer <mail@david-bauer.net>
(cherry picked from commit 20eb45da4fc19c12ea2073471992eeaf9d602fa5)