Good Someone who has the time can do patches. I also have for 6.0,6.1 and version 14.
Also one small fix for 6.2 version i forgot.
Put this in /etc/config/system
config led
option sysfs 'tl-wr840n-v6.2:green:lan'
option trigger 'netdev'
option name 'LAN'
option default '0'
list mode 'tx'
list mode 'rx'
option dev 'eth0.1'
config led
option default '0'
option trigger 'phy0tpt'
option sysfs 'tl-wr840n-v6.2:green:wlan'
option name 'WLAN'
config led
option name 'WAN'
option trigger 'switch0'
option port_mask '1'
option sysfs 'tl-wr840n-v6.2:green:power'
So leds are going to be fine Test it !