mac80211: in AP mode, set bss_conf::he_supported

In AP mode, If AP advertises HE capabilities, set to true
bss_conf::he_supported so that the Driver knows about it.

Signed-off-by: Shaul Triebitz <shaul.triebitz@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>