ath79: include rssileds package for ubnt devices with LEDs

ath79: include rssileds package for ubnt devices with LEDs

Some Ubiquiti devices had the RSSI LEDs configured in 01_leds but
were missing the rssileds package, while others that don't have
RSSI LEDS had the package included.

This commit includes the rssileds package only for those devices
that need it.

Tested on a NanoStation M XW.

Signed-off-by: Roger Pueyo Centelles <roger.pueyo@guifi.net>
(cherry picked from commit 1c6066a867400eca9e335235ff4dc43acacc1183)
[backported to 19.07]
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>