ath79: change Ubiquiti UniFi AP model name to include "AP"

ath79: change Ubiquiti UniFi AP model name to include "AP"

While it hasn't always been clear whether the "AP" is part of the model
name on the Ubiquiti website, we include it for all other pre-AC
variants (AP Pro and the AP Outdoor+). Add it to the original UniFi AP
as well for consistency.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
(cherry picked from commit dc23df8a8ca728871d84f0a140f4b52c36b03f1d)