The call "get_features" allows to gather hostapd config options
via ubus. As first infos we add the ht and vht support.
Although nl80211 supports to gather informations about
ht and vht capabilities, the hostapd configuration can disable
vht and ht. However, it is possible that the iw output is not
representing the actual hostapd configuration.
Signed-off-by: Nick Hainke <vincent@systemli.org>